In this chapter, we provide an overview of modern methodological approaches to relationship science that is both practical and accessible. We start with a “status report” on the field, outlining three popular methodological trends. First, we discuss the application of machine learning techniques, specifically random forests, to the field of relationships science. Second, we elaborate on the importance of multimodal data, describing studies incorporating physiological, neurological, and linguistic measures. Third, we briefly discuss nonstandard dyadic designs, such as the round-robin design and network analysis, which enable the examination of multiple dyads within larger groups. Throughout these sections, we provide recommendations for scholars who wish to implement these methods in future work. Next, we provide a description of two analytical approaches used frequently in dyadic data analysis – structural equation modeling (SEM) and multilevel modeling (MLM) – and discuss the strengths and weaknesses of these approaches. We also present a brief discussion of differences between statistical software programs and suggestions for when to use each.

In the current chapter, we review the research on close relationships done via the methodologies of neuroscience – in short relationship neuroscience (RN). Much of the research we review focuses on attachment (child–parent or romantic) and sexuality. Nevertheless, we aim to cover RN broadly defined. We start by framing our topic and providing a few working definitions. We then cover the various relational (attachment, interdependence) and neuroscience (social baseline theory, and the Functional Neuroanatomical Model of Human Attachment) theories, methodologies (MRI, ERPs, and genetics), and types of relationships (familial relations, romantic, friendships, sexual relations, etc.) used or covered in this subfield. We explore both positive and negative aspects of close relationships. Finally, we reflect on the bidirectional link and contributions between relationship science and neuroscience and suggest potential implications for mental and physical health and policymaking. We also outline some remaining issues and future directions for RN.

There has been a growing body of research examining the longitudinal course of couple relationships. In this chapter, our goal is to synthesize and critically evaluate the research on long-term couple relationships, highlighting what we have learned and the advances that have been made to earlier work, while being inclusive of a variety of methodological and analytical approaches. We discuss early studies on long-term relationships; research assessing the different pathways of development as well as the antecedents, correlates and outcomes of various patterns of change; and the crucial role of self-help advice and intervention/prevention programs for fostering long-term couple relationships. We argue that although there has been progress in this area, the research still lacks much-needed diversity, and we consider broader limitations and directions for future research.

As society continues to change, so, too, has the nature of social connections between people. This chapter, however, focuses on one relationship immutable: that people often maintain committed involvements with particular others. We begin by situating and defining relationship commitment within a modern social context. We review historical and current theoretical models of commitment, including coverage of hypothesized antecedents, emphasizing empirical findings on precursors of commitment since the last edition of the Handbook. We then turn to reviewing research on hypothesized consequences of commitment, again emphasizing empirical findings since the last edition. Recent research considering racial, ethnic, and cultural variations in commitment is also reviewed. We conclude the chapter by offering possible future directions for commitment research.

This chapter is a review of evidence-based relationship education (RE), meaning education to promote healthy couple relationships whose content is informed by the psychology of intimate relationships, and evaluated in methodologically rigorous trials. We describe two broad approaches to RE and their theoretical underpinnings: assessment with feedback and curriculum-based RE. The chapter analyses how RE can be tailored for different stages of the family life cycle and made easily accessible by using different modes of delivery (e.g., face-to-face, online, and via apps on smart devices). The effectiveness of RE approaches and the factors influencing RE effects are summarized via an umbrella review of recent meta-analyses of outcome research. We conclude that future directions for research and practice should include expanding the diversity of RE theory and content to address diversity in culture, life circumstances, and gender diversity of couple relationships; and extending the reach of RE.

People enact meaningful personal relationships using communication technologies. The current chapter overviews how technology and personal relationships are intertwined. The perspective of the chapter is centered on how people relate via technologies while recognizing the importance of understanding the technologies themselves and how they are used. The chapter has three main sections. The first examines how communication technologies are integral to relational communication across the course of relationships, and the second considers factors that shape the nature and impact of relational communication occurring via technologies. The third section focuses on both relationships and technologies by considering the contemporary notion of mixed-media relationships, which are enacted via multiple channels, often simultaneously. Finally, the conclusion of the chapter elucidates some key complexities and their implications for future research and theory, including the need to consider both technologies and messages simultaneously and the challenges of analyzing multimodal communication in relationships.

Friendship is a consequential relationship for child development and well-being. This chapter examines recent research on three major themes related to children’s friendships. We begin by reviewing findings from several long-term longitudinal studies documenting the diverse and multifaceted impacts of childhood and adolescent friendship competencies and experiences on later adjustment. We also highlight how these long-term longitudinal studies have allowed researchers to test and refine theoretical perspectives about how early family and peer relationships facilitate the development of skills and understandings that set the stage for social competence and positive adjustment later in development. With this as background, we review theory and research on the processes and provisions that characterize children’s friendships, and then describe important contextual factors that affect children’s friendships, with a particular focus on the school context and how contextual factors can facilitate or undermine the development and maintenance of cross-group friendship.

Despite variation in their social needs and experiences, all humans require social connections to thrive. When humans lack fulfilling connections, they experience loneliness. However, while seemingly simple, loneliness is a multidimensional construct arising from varied social deficiencies and leading to varied psychological experiences. This chapter reviews the literature on loneliness, describing what it is, why we experience it, its prevalence and consequences, and what is being done globally to address it. In doing so, we highlight the considerable impacts of loneliness on individuals and society, its complexity, and the opportunities for future work. We close acknowledging the significant advancements made in loneliness research over the past several decades and highlight how this knowledge is being mobilized to advance the prevention and treatment of loneliness. In doing so, we hope this chapter serves as a useful starting point for understanding the problem of loneliness and the challenge of addressing it.

The current chapter focuses on basic properties of communication that inform the ways that the study of communication and the study of relationships intersect. These properties include interdependence (the idea that messages simultaneously influence and are influenced by messages that precede and follow them), reflexivity (the notion that communication creates and is constrained by structure), complexity (the concept that communication conveys multiple messages and functions at different levels of analysis), ambiguity (the notion that any given message has various meanings), and indeterminancy (the idea that messages can have multiple and diverse outcomes on relationships). Research on relationship narratives, message features, multiple goals, and message processing, among other topics, is reviewed and challenges for researchers who study communication and relationships are discussed.

In this chapter I focus on the nature of theories in the social sciences, some philosophy of science behind the validation of theories (e.g., falsifiability, approaches to deciding the value of evidence for/against a theory), and some issues to consider with respect to the research process and theory development and evaluation. I discuss the value of deconstructing theories to assess their core and auxiliary assumptions and determine aspects of a theory that have yet to be examined. I also discuss modern approaches to assess the evidentiary value of this body of research. I suggest that in our interdisciplinary field, researchers should consider generating hypotheses, as well as research explorations, through carefully evaluating and questioning the assumptions of the theories typically applied in the study of personal relationships. This discussion includes the use of modern approaches such as computational models. The overarching theme of the chapter is that as a field we need to evaluate and develop our theories using some recommendations put forward for decades combined with recently developed techniques in order to advance our theories beyond vague verbal statements that are interesting yet not precise to theories that allow for more consistent deductions of specific hypotheses.

What is the effect of one’s personality on one’s close relationships? In this chapter, we review the literature on this topic, focusing especially on the personality dimensions of self-esteem and the Big 5 traits of neuroticism and agreeableness. We review empirical studies of each of these three traits as predictors of (a) interpersonal processes and (b) relationship outcomes, including relationship satisfaction and dissolution. We also summarize any existing theoretical perspectives on these associations, including the most complete theoretical account offered for the influence of any of these traits on relationships—namely, the Self-Esteem-Infuses-Relationships-through-Trust (SIRT) model. We expect that two core assumptions of the SIRT model would be fundamental to theoretical accounts concerning any personality dimension’s influence on relationships. Specifically, (a) any trait?s influence must exert its influence through a causal chain of mediators, and (b) one of the essential mediators is behaviors between partners. Finally, we also evaluate how complete theoretical accounts concerning neuroticism and agreeableness that are likely to be offered in the future are likely to differ from or be similar to the account for self-esteem offered by the SIRT.

This chapter addresses intimate relationships of Black populations, as well as the sociocultural and economic contexts in which they are embedded. The authors underscore the heterogeneity of Black populations both in, and outside of, the United States. How racial discrimination is experienced, and the impact of that experience, differs across Black populations – underscoring heterogeneity. While some research suggests that racial discrimination contributes to negative relationship dynamics, other work suggests that when some individuals experience racial discrimination their partners engage in supportive behaviors. Despite declines and delays in marriage, many U.S.-born Blacks are still pursuing marital unions and are happily married (Skipper & Taylor, 2021; Skipper et al., 2021). This is likely a function of relational resilience, or even the Black Advantage Vision as many U.S. Black couples adapt and strive in spite of seemingly unsurmountable stressors over which they have little control.

Relationship development and growth have long drawn the interest of relationship scholars. This chapter focuses on the theoretical frameworks that have guided inquiry. We begin by explicating the term relationship development, including different ways researchers have studied it. Traditional theories (e.g., relational dialectics, relationship stage models, social exchange, social penetration, relational turning points) are described, alongside recently developed perspectives on relationship development and growth (e.g., relational turbulence theory, the relationship trajectory framework). The chapter also discusses current research associated with the theories and how this scholarship informs our understanding of the initiation of relationships and how relationships develop over the lifespan. Special attention is paid to the development and maintenance of marginalized relationships. The chapter concludes with suggestions for future research, including the need to assess the ability of current theories to describe development in different relationship contexts (e.g.., friendships, courtship, families) and in different communication contexts (e.g., online, offline).

Aggression in an intimate relationship violates commonly held expectations that a romantic partner will be loving and supportive. Partner aggression erodes the quality of a relationship and can cause people to experience significant psychological distress and pain. This chapter critically examines research on features of aggression in relationships, how partner aggression is regulated and maintained, and interventions and efforts to address partner aggression. We aim to convey the current state of research on partner aggression and suggest new directions for research.

This chapter reviews the literature on responses to wrongdoing in close relationships. We begin by discussing what we know about transgressions as they occur in relationships. We then explore research and theorizing on three related but distinct ways of responding to wrongdoing (forgiveness, unforgiveness, and revenge) that vary in the nature of the response, the research attention they have attracted among those who study relationships, and the extent to which they are viewed as appropriate, desirable, and healthy. We also consider directions for future research and comment on how current methodology and theory can be extended in this area. We ultimately encourage relationship scholars to approach investigation of relational wrongdoing with openness to the possibility that forgiveness may not always and inevitably be the best way forward by exploring when, for whom, and under what circumstances both forgiveness and its less favourably viewed alternatives produce desirable versus undesirable outcomes.

This chapter presents an overview of recent trends and developments in research on close relationships. It is a sequel to the chapters that appeared in earlier editions of this Handbook (Perlman et al., 2018; Perlman & Duck, 2006) and thus reviews the developments in relationships research from 2016 to mid-2023. Drawing on data from a survey of authors of articles published in Personal Relationships and the Journal of Social and Personal Relationships and a bibliometric analysis of these papers, we discuss the scholars who relationship scientists perceive as eminent and who they feel are emerging as influential. We use these data to highlight the major theories, methodological trends, and substantive foci that have been the foundation of relationships research since 2016. Comparison with earlier versions of the chapter reveals stability in the field’s preoccupations but also demonstrates how it has responded to contextual factors within and outside of academia.

Romantic love seems to be a nearly universal phenomenon, appearing in every culture for which data are available and in every historical era. This chapter first reviews research on how ordinary people construe love. Then it turns to how researchers have understood and measured love, organizing its discussion around the theme of types of love. Next it covers the course of love with a focus on falling in love. It then reviews several approaches that have been particularly influential in specifically focusing on understanding the dynamics of romantic love, especially with regard to passionate love. It concludes with a brief review of the work on other kinds of love in relationships. The authors hope that this review has conveyed their view that the study of love is both important and a thriving scientific endeavor, offering both a solid foundation and vast opportunities for significant future work.