The development of romantic relationships commonly begins in adolescence and continues to unfold over the life course. Over the course of time, a romantic relationship may take on new characteristics, acquire new meaning, and serve new functions (Furman & Collins, 2009). For example, the attachment and caregiving behavioral systems typically become more salient as the relationship develops (Furman & Wehner, 1994).

Of particular importance are the formative experiences and developmental processes that occur during emerging adulthood. The salience of romantic relationships increases across these years, rivaling and sometimes surpassing those with parents and eclipsing those with friends (Laursen & Williams, 1997). Many emerging adults face decisions about long-term commitment, including cohabitation and marriage.

Not only do particular romantic relationships change and develop but also changes can occur across relationships. Emerging adulthood is often a time of exploration, and many persons during this period have a series of different romantic relationships. As relationship experiences accumulate, patterned styles of interacting with romantic partners may emerge or change (Laursen & Jensen-Campbell, 1999). These developmental processes are complicated and multiple in nature. One of the key questions social scientists face is how best to capture the changes and development that occur in romantic relationships and experiences in emerging adulthood.

Over the last two decades, statisticians have developed a range of different statistical procedures to analyze change and development. Traditionally, autoregressive models were the method of choice with longitudinal data.

For most American adolescents, romantic relationships begin as a remarkable mystery. What's this weird feeling deep in the pit of my stomach? How do I get someone to like me? How do I know if someone I like likes me back? What should we do together? What can we talk about? How can I tell if someone really loves me or is just trying to take advantage of me? If we start having sex, will it change the relationship? Why don't my parents understand that my boyfriend/girlfriend and I need to spend lots of time together? These are mysteries that nearly all American adolescents must confront; they are a part of growing up. For help with such issues, adolescents may turn to friends or family members or even television shows. But at present there is little reason for them to turn to social scientists for insights because research on this topic has been surprisingly sparse.

Investigators have not ignored the topic entirely. Descriptive information on dating has been gathered periodically (e.g., Gordon & Miller, 1984; Hansen, 1977; Roscoe, Cavanaugh, & Kennedy, 1988), and some ethnographers have studied peer group processes and romantic relationships (Dunphy, 1969; Eder, 1985).

Adolescent romantic relationships have received little attention from social scientists, as they have been considered to be ephemeral experiences of little significance. In contrast to this view, the authors in this volume provide a rich and varied set of theoretical ideas concerning the nature of adolescent romantic relationships. What is most striking from reading these chapters is the complexity of these relationships.

This complexity is evidenced in many ways. Witness the diversity of theoretical perspectives taken in this volume, not only across the different chapters but even within a particular one. For example, Gray and Steinberg draw on sociobiological and contextual views of family functioning. Laursen and Jensen-Campbell integrate social exchange and evolutionary theory. Larson, Clore, and Wood incorporate three theories of emotions. Miller and Benson describe the contribution of both biological and cultural processes.

The descriptions of the relationships are equally complex. Connolly and Goldberg discuss emotions, behaviors, motives, and concepts. Downey, Bonica, and Rincon delineate how rejection sensitivity may be played out in terms of relationship processes, partner selection, and the impact of being rejected by a partner. Gray and Steinberg describe multiple mechanisms that may link romantic relationships and the family of origin, and Collins and Sroufe present a series of processes that would lead securely attached individuals to be more able to navigate the new tasks entailed in dating.

Romantic relationships are a new and exciting arena for adolescents. As they embark on these relationships, they try out unfamiliar behaviors, experiment with different ways of interacting, and acquire new skills. They have to make sense out of many novel, often surprising experiences. Much time is devoted to thinking or talking about their boyfriend or girlfriend and their relationship. They may wonder what a particular interaction meant or how each feels about the other. Sometimes they mentally enact different hypothetical scenarios with romantic partners, using past relationship experiences to anticipate their own and their partner's response to a given situation.

These thoughts, beliefs, and expectations concerning romantic relationships vary from person to person. For example, when faced with a family problem, one adolescent may think that she should turn to her partner to seek comfort and guidance. Another may feel that she should keep the problem to herself, fearing that the other would consider the problem to be insignificant and would not be interested. A third may feel it is important to seek out her partner, yet may think she is likely to be dissatisfied with the other's effort to comfort her. Such thoughts or representations of relationships are expected to guide an individual's behavior and serve as a basis for predicting and interpreting others' behavior.