Defining and Measuring the Complexity of Stepfamilies in the United States

Lindsey Aldrich, Karen Benjamin Guzzo, Susan L. Brown, and Krista K. Westrick-Payne

Download brief


Stepfamilies are common in the United States. By definition, these families occur when an individual or the person with whom they are partnering through marriage or cohabitation has a child from a past relationship.1 There are many types of stepfamilies, however, which makes it difficult to track and define these family forms and draw conclusions about how various types of stepfamilies function.2

Regardless, programs seeking to work effectively with stepfamilies can benefit from knowing more about the complexity of this family form. Some healthy marriage and relationship education (HMRE) programming, for example, is designed or, more often, modified to be used specifically with stepfamilies.3 To support stepfamilies most effectively, it is critical for HMRE programming to understand and respond to different forms of stepfamilies.

In this brief, we synthesize what research published in the last decade tells us about stepfamilies among individuals of childbearing age who have minor-age children. We begin by discussing how stepfamilies differ from other family forms in the United States and review the different pathways into a stepfamily. We also review recent estimates of stepfamilies in the United States, highlighting some of the measurement and data-related challenges in determining these estimates. We conclude by discussing gaps in current research and implications for HMRE programs designed to support stepfamilies.

Key findings and implications

  • Stepfamilies are common.
    • Among adult Americans under age 50 who were living with a partner in 2017, 35 percent of women and 25 percent of men were in a stepfamily.
    • In 2019, nearly 1 out of 10 children were living in married or cohabiting stepfamilies.12
  • Stepfamilies are complex and can be formed in various ways.
  • Future research should:
    • Identify stepfamilies, cohabiting and married, from the perspective of all family members.
    • Incorporate nonresidential children when defining a stepfamily.
    • Attend to the diversity within stepfamilies across factors such as marital status, sexual orientation, race/ethnicity, socioeconomic status, and education.
  • HMRE programming should consider the diversity of stepfamilies when designing, implementing, and evaluating programs, recognizing that there will be no “one size fits all” program.

The Uniqueness of Stepfamilies

Stepfamilies are often healthy and fulfilling for family members. However, some stepfamilies face unique challenges and stressors, in part because they lack many of the legal protections, expectations, language, and norms that accompany biological-parent families.13 For example, when it comes to parental rights, stepparents do not have the same legal standing as biological parents. Many stepfamilies cannot rely on traditional language to refer to other members in their stepfamily; some stepchildren may call their stepparent “mom” or “dad;” others may call their stepparent by their first name; and still others create their own labels altogether.14 Stepfamilies formed when children are young often differ substantially from those formed when children are older in terms of how people relate to each other;15,16 similarly, stepfamilies formed after the death of a partner/parent are different from those formed after divorce.2

The variability in how stepfamily members relate to each other reflects a wide range of family dynamics within these families. In some stepfamilies, co-parenting relationships across households—both between former partners and between a biological/adoptive parent and a stepparent—work smoothly; in others, they are more contentious.17 Some children split time across households and family structures,18 and some children are part of more than one stepfamily (if both of their parents form new relationships). Some parents have residential and nonresidential biological children, and others live with stepchildren but not with their own biological children;19 some children may have step-siblings, others half-siblings, and still others may have a mix of full-, half-, and step-siblings. The expectations within a stepfamily—stepparents’ obligations and responsibilities for stepchildren or the extent to which individuals feel they should provide support and assistance to step- or half-siblings—can vary considerably,20 and biological parents may feel as if they have competing obligations between their relationship with their partner and their relationship with their child(ren).21

Family Change over Time

The United States has witnessed sizeable shifts in family behaviors over the past few decades. Americans are waiting longer to marry,4 and a growing number of individuals do not marry at all during their childbearing years.5 Additionally, cohabitation has become increasingly common,6,7 though these unions are less stable than marriage and less likely to transition to marriage than they were in the past.8,9 Divorce rates have declined modestly in recent years; however, they remain high with less than half of all marriages ending in divorce.10,11 All these trends shape the formation of stepfamilies.

Stepfamilies also tend to be less stable than two-biological-parent families in which neither partner has a child from a prior relationship.22,23 The reasons behind the somewhat greater instability of stepfamilies include some of the stressors noted above (lack of guiding norms or tensions arising from competing obligations) and potentially less fear of divorce or separation, having already survived one in the past. Although children in stepfamilies often benefit from the additional economic resources provided by the stepparent (relative to living in a single-parent family), the financial benefits are often offset by challenges linked to the instability, transitions, and more complicated family dynamics that often accompany stepfamily formation. As a result, children in stepfamilies generally do not fare appreciably better (or worse) than children in single-parent families across a range of educational, social, cognitive and behavioral outcomes.24

To better understand the varying dynamics within stepfamilies, in this brief we review the different pathways into and types of stepfamilies and identify the prevalence of stepfamilies. The following sections will show how and why these tasks can be challenging.

Identifying and Measuring Stepfamilies

Stepfamilies are complex. From a parent’s perspective, stepfamilies occur when at least one of the adults is not biologically related to the children in the family or has children from a prior relationship.2 From a child’s perspective, a stepfamily occurs when their biological or adoptive parent marries or lives with a non-biological parent (who may or may not have a child from their own prior relationships and who would be the child’s step-sibling) or when a child lives with both biological or adoptive parents but has a half-sibling from one or both of their parents’ prior relationships.

Stepfamilies can be formed through a person’s first marriage, remarriage, or cohabitation. In recent decades, stepfamilies are less often formed after the death of a partner or parent than in the past; most stepfamilies today occur after a break-up.2 Figure 1 outlines five common pathways in which an individual may enter a stepfamily.

Not only are there different pathways into a stepfamily that can make studying stepfamilies challenging, but measuring and defining stepfamilies is often inconsistent across national survey data, and many datasets contain limited information that could be used to identify stepfamilies. For instance, a survey may not collect information about the respondent’s partner’s past relationships—that is, does the respondent’s partner have children from a prior relationship? (For a more detailed discussion of the challenges of studying stepfamilies with survey data, see the Method section at the end of the brief.)


Stepparent is an adult whose partner has at least one child from a previous relationship.

Step-siblings are not genetically related at all; that is, they do not share any biological parents.

Half-siblings share/have one biological parent in common.

A complex stepfamily occurs when both partners have children from a prior relationship while a simple stepfamily occurs when only one adult is a stepparent in the stepfamily.

Source: Ganong & Coleman, 2017

Data collection considerations for studying stepfamilies

Cross-sectional versus longitudinal data

Studying stepfamilies using survey data and nationally representative data sources is also challenging because families change over time. Many cross-sectional, nationally representative data sets collect information from different people each time they collect survey data (e.g., the American Community Survey). A benefit of these data is that it provides information on national patterns of family structure at one point in time. However, this “snapshot” approach misses the movement of individuals into and out of stepfamilies (or any family structure) over time. Other datasets follow and collect information from the same respondents over the years, which allows researchers to produce longitudinal analyses that capture the patterns and behaviors of that same group of respondents across parts of their lifetime. However, such data tend to be based on smaller samples and less representative of the larger population.

Challenges identifying stepfamilies using measures of family structure

Some projects identify stepfamilies by looking at family structure, which refers to children’s living arrangements.25 Specifically, family structure measures children’s relationships to parents in the household. For instance, children may live with two married or cohabiting biological or adoptive parents, a biological mother and a married or cohabiting stepparent, a biological father and a married or cohabiting stepparent, a single mother, a single father, or in other household types, such as with grandparents or other living arrangements. Stepfamily experiences among those in same gender relationships, often identifying as lesbian or gay, are often ignored, yet the pathway to parenthood for same gender couples often is based on stepfamily formation because both parents are not biological parents.26

Focusing on family structure that emphasizes relationships to parents likely excludes some stepfamilies. For example, a child may live with their biological mother and father as well as an older half-sibling from one of their parent’s previous marriages. Within this family, the two children (i.e., the younger half-sibling and older half-sibling) have two different family structures—the younger half-sibling lives with married biological parents, while the older half-sibling lives with a parent and a stepparent. The term family complexity has emerged over the past decade to better account for the presence of half-siblings or step-siblings in the family,25 although the negative connotations with the term “complexity” can be problematic.

Challenges identifying stepfamilies using household rosters

It is not possible to identify stepfamilies in all data sources. For example, large surveys often create a list of people in the residence (referred to as a “household roster”) and then identify how each person on that list is related to the person who filled out the survey (referred to as the “respondent”)—but not necessarily to each other person in the household.2 In doing so, they get only a partial set of relationships among the people living together. Further, this approach does not determine how children are related to one another, so it is difficult to establish whether children share the same parents. For example, if a mother has two children by different partners, lives with both of those children, and lives with one of those fathers, it could be determined that these are her children but would not reveal that the children are half-siblings and that this is a stepfamily. Even when relationships between household members are established in surveys, they typically exclude individuals who live outside the home. Consider a scenario in which a woman is married to a man whose children live elsewhere with his ex-partner; unless there is information on nonresidential children, this family would not be identified as a stepfamily. Given the growth in stepfamilies, surveys may need to be more deliberate and ask questions to establish family relationships within and outside households.

Individual versus couple level data

Many data collections interview a main respondent about their own relationship and parenting experiences but do not collect much information about their spouse or partner’s past relationship and childbearing experiences. Establishing both members of a couples’ relationship and childbearing experiences is critical for identifying stepfamilies. For example, the National Survey of Family Growth asks respondents whether each current or past partner had been married before or if they had children from a prior relationship (regardless of if those children reside in the household). Collecting information about the main respondent’s relationship and childbearing history and a partner’s history would result in datasets better able to identify complex stepfamilies in which both partners have children from prior relationships. If two divorced parents remarry each other, but there is information about only one of those parents’ past experiences, researchers will be unable to discern how members work together and function in the presence of different and sometimes competing obligations.

Some surveys interview both members of a couple or both parents of a child—that is, they are dyadic. Dyadic surveys are relatively rare but may be the most accurate way to identify stepfamilies, because information can be gathered directly from each partner about current and past relationship experiences and childbearing. The Fragile Families and Child Wellbeing (Fragile Families) study, for instance, interviews both parents. Moreover, it is a longitudinal survey and follows parents over time, allowing it to measure when they break-up and form new relationships. Not only does this type of survey enable researchers to capture children’s lifetime exposure to stepfamilies, it also identifies situations in which children belong to two different stepfamilies. That is, if both parents re-partner through cohabitation or marriage, that child would be a part of two separate stepfamilies. Few datasets can capture that type of situation.

Simplifying the measurement of stepfamilies

One potential way to simplify identifying stepfamilies would be to ask individuals direct questions about being in a stepfamily. However, the chances that people use the “step” label when talking about their family members may depend on the nature and quality of those relationships and may vary over time.14,27 Members of what appear to be the same family may not readily identify themselves or their relationships in the same ways. Members of recently formed stepfamilies may not consider themselves part of a stepfamily as quickly as someone who has been a part of a stepfamily for many years. Further, older adult children who did not grow up with a stepparent may not identify with the stepfamily label if their parent(s) form a new relationship well after they have stopped living with their parents. Additionally, individuals can be resistant to claim stepfamily members they do not know or with whom they do not have good relationships. Conversely, individuals can be resistant to apply the “step” label to some family members because they have close, strong quality, or long-term relationships with these people and want to avoid labeling them in a way that suggests they have weaker ties than if they had a biological relationship. Finally, broad social and cultural contexts, such as laws, religion, and media, influence whether individuals feel comfortable using the ‘step’ family label, especially because stepfamilies have often been stigmatized in the past.27

Prevalence of Stepfamilies

While it is clear that stepfamilies are common,20 how common depends on how and from whose perspective they are measured.

Adults in stepfamilies

For instance, among adult Americans under age 50 who were living with a partner in 2017, 35 percent of women and 25 percent of men were in a stepfamily in which either they had children from a previous relationship themselves and/or had a partner who had children from a previous relationship.28

Over the past several decades, a new picture of stepfamilies has developed. For example, in 1988, one fifth of all women ages 15 to 44 in a stepfamily union were living in a cohabiting union, with the remaining four fifths living in a marital union. By 2017, the share who were cohabiting had doubled to two fifths. As shown in Figure 2, changes have also occurred in the composition of children in the family (which partner has children from a prior relationship). In 1988, just more than a fifth of women ages 15 to 44 living a stepfamily reported that they lived in a complex stepfamily—that is, that both she and her partner had children from a prior union. By 2017, that share grew to more than one third. Notably, cohabiting stepfamilies are more likely to be complex stepfamilies—with both partners having children from a past relationship—than are married stepfamilies.

Children in stepfamilies

In 2021, just more than 1 in 10 children were living in married or cohabiting stepfamilies.29 Just more than a third of children living in a stepfamily were living in a cohabiting, rather than a married, stepfamily, though overall less than 1 in 25 children in the United States lived in cohabiting stepfamilies in 2021.29 This is a “snapshot,” however; many more children will live in a stepfamily for some period of time during their childhood. In 1995, it was estimated that one third of all children would live in a stepfamily at some point; the data to estimate such probabilities for children born more recently are unavailable30 but it is likely that the share has only increased given shifts in nonmarital childbearing, cohabitation, and marriage over the past three decades.

Stepfamilies formed through higher-order unions

After an individual’s first cohabitation or marriage, each subsequent cohabiting union or marriage is considered a higher-order union. The more cohabitating or marital unions an adult has had, the higher the order of their current union (e.g., second, third, or more). Married or cohabiting stepfamilies do not necessarily have to be higher-order unions; they can be formed through a first marriage or cohabitation if either partner has a child from a past relationship (regardless of whether that relationship involved cohabitation or marriage). It is also important to note that a first union for one partner could be a higher-order union for the other partner.

Stepfamilies are more common in higher-order unions than they are in first unions.31 Among women of childbearing age, roughly one quarter of first cohabitations or marriages were stepfamilies, while two thirds of second cohabitations and marriages, and three quarters of third cohabitations and marriages constituted a stepfamily.31 Only about 3 in 20 first marriages include stepchildren,32 while roughly 1 in 4 marriages overall and nearly two thirds of remarriages include stepchildren.33

Stepfamily composition and residency

Mother-stepfather stepfamilies make up nearly 80 percent of all residential stepfamily households in the United States;34 however, it is important to recall that the primary way to identify a stepfamily is by establishing the ties between adults and children who reside together. Many father-stepmother stepfamilies are likely being missed because fathers are less likely to have physical custody of their children;35 a father and his new partner may live together but would often not be identified as a stepfamily if his children live elsewhere. Further, a focus on residency and reliance on the parent’s perspective can miss step- and half-siblings outside the household and even sometimes within the household, depending on how ties within a household are delineated. Additionally, children whose parents have shared or split custody can be overlooked in counts of stepfamilies. The most accurate counts of stepfamilies would consider the family structure from all family members’ perspectives, including parents and siblings who are outside the household.

Among women ages 15 to 44 in a stepfamily in 2006-2013 that was formed via remarriage, there was a wide array of composition and living arrangements as shown in Figure 3. In these women’s stepfamilies, for instance, just more than a fifth did not have a stepchild living in the household.

Implications for Future Research

Our review of the literature found considerable variation in defining and identifying stepfamilies in and across nationally representative survey data. This variation has implications for studying stepfamily dynamics, functioning, and stability. It may be difficult to generalize from the types of stepfamilies studied in these surveys to the larger population of individuals in more complex or harder to identify stepfamilies. Future research focusing on stepfamilies should be clear on what constitutes a stepfamily or who counts as a stepfamily member.36 Additionally, many surveys and datasets fail to capture family members who live elsewhere; this causes nonresidential family members (such as a child living elsewhere) to be missed. For instance, a stepfamily formed between a childless woman and a father whose children live elsewhere would not be identified as a stepfamily if there is no information on nonresidential children. New data collections should make a concerted effort to collect information on family members living outside the home and do so not only for the main respondent but others in the family, such as children and partners.

Also, overall prevalence estimates of stepfamilies often overlook the diversity within stepfamilies (and likely their link to outcomes such as relationship quality, stability, and well-being) across factors such as marital status, sexual orientation, race/ethnicity, socioeconomic status, and education. Although there is some work demonstrating variation in well-being across types of stepfamilies14 and differences in family behaviors across sociodemographic characteristics,37 we caution that these comparisons may lead to conclusions that some stepfamily types are inferior or superior. More work is needed that explicitly considers how well-being in stepfamilies is linked to broader systems of oppression and marginalization, in terms of whether individuals from marginalized groups are more likely to live in a stepfamily at some point and whether stepfamilies themselves are stigmatized and discounted in various institutions and policies that tend to privilege married families with only shared biological children.

Finally, the dynamic nature of stepfamilies—at an aggregate level within a population and at a smaller level within families or within an individual’s personal experiences—means that the field needs a variety of research questions and research designs. For instance, any prevalence estimate of stepfamilies is simply a “snapshot” of who is living in a stepfamily at a given moment in a given population, rather than a measure of the population who may ever be in a stepfamily. To measure trends, researchers should repeat those “snapshots.” However, longitudinal analyses following the same people over time are needed to understand the lived experience and longevity of stepfamilies. Understanding how adults and children enter and exit stepfamilies, their experiences within stepfamilies, and the relationships that exist after stepfamily dissolution requires different types of data and research designs.

Implications for Practice

In addition to research priorities, human services programs that work with couples and parents should consider the diversity of stepfamilies especially for how they differ from first marriages/relationships and from each other. Healthy marriage and relationship education (HMRE) programs designed for stepfamilies primarily focus on building relationships between children, parents, and co-parents through problem solving, communication, conflict resolution, and communication about financial issues,38,39,40 consistent with HMRE programming generally. 3 However, a unique focus for some HMRE programs for stepfamilies is on debunking myths about stepfamilies and on understanding the unique characteristics of stepfamily relationship dynamics and relationship functioning.41 For example, HMRE practitioners may acknowledge that couples in a stepfamily may be at greater risk for relational instability and dissolution39 and take steps to address that risk through program activities and other curriculum content. Also, HMRE programming focused on stepfamilies could help couples deal with tensions that may arise between step-siblings, which have the potential to negatively influence a couple’s own relationship; programs could help parents develop strategies to facilitate close and supportive relationships among family members. Relatedly, coparenting can be a common source of conflict for stepfamilies. Community-based programs have helped couples in stepfamilies improve coparenting and parenting skills within and across households.42 However, a recent review of stepfamily relationship education reveals that the practice field has not kept pace with the broader research focus on the complexity of stepfamilies, and more work is needed to design, implement, and evaluate HMRE program models that better meet the needs of complex stepfamilies.41


This brief drew on studies published since 2010 that used nationally representative U.S. data, although it also incorporated some studies outside of these parameters when more recent research or studies using nationally representative data were not available.


About the Authors

About the MAST Center


Our Partners