Social and Personality Psychology Compass 9/11 (2015): 630–643, 10.1111/spc3.12205 Play Behavior and Playfulness in Adulthood Meredith Van Vleet * and Brooke C. Feeney Carnegie Mellon University Abstract Although research has established play behavior and playfulness as important to the well-being of children and animals, researchers have not typically considered the importance or implications of play in human adults. This is surprising given that play behavior is a topic of high relevance to social psychology. Defi- nitional issues, a lack of a theoretical framework, and a dearth of standardized measures have posed obsta- cles in the advancement of this interesting research area, which is ripe for investigation. In this review, we summarize the extant literature, identify strengths and weaknesses of this literature, propose definitions to guide future work in this area, identify relevant theories that may be expanded to provide a framework for programmatic research on play in adulthood, and elucidate avenues for future research. Our aim is to encourage the development of this research area within social psychology. Play Behavior and Playfulness in Adulthood We don’t stop playing because we grow old; we grow old because we stop playing -George Bernard Shaw Play is thought to be universal and essential to the healthy development and well-being of young mammals (e.g., Power, 2000; Thorpe, 1966; Wilson, 1975). Play has been associated with social, emotional, and cognitive development (including problem-solving abilities) in young animals (Fagan, 1981; Harlow & Harlow, 1962) and children (e.g., Coolahan, Fantuzzo, Mendez, & McDermott, 2000; Fantuzzo & McWayne, 2002; Fantuzzo, Sekino, & Cohen, 2004; Shonkoff & Phillips, 2000). Play behavior and playfulness also have been linked with creativity and imagination (Singer, Singer, & Sherrod, 1980), adaptability (Sutton-Smith, 1970), high self-esteem, and autonomy (Barnett, 1991) in children (see also Tamis-LeMonda, Shannon, Cabrera, & Lamb, 2004). Surprisingly, however, research on play and playfulness in human adults is scarce. Despite the paucity of empirical attention devoted to play in adulthood, adults often describe the most enjoyable element of their romantic relationships as interactions in which they play with their partner (Betcher, 1981; Lauer & Lauer, 2002). When a sample of married couples were asked what they would miss most if their relationship were to dissolve, couples most often reported their inside jokes and games (Betcher, 1981). Along similar lines, Lauer and Lauer (2002) found that highly satisfied couples described play as an essential feature of their relationship – even more important than sex or shared humor. Why, then, have researchers, particularly social psychologists, not further explored this phenomenon? One possible explanation for the void of research examining play in adulthood is that some propose that play is not socially accepted in adulthood, and adults play little or not at all as a result (Lieberman, 1977; Solnit, 1998). Adults are expected to be productive – whether at work or at home. If play is not viewed as a productive means to spend one’s time, then play among adults © 2015 John Wiley & Sons Ltd