The chapter examines the importance of online social interactions and relationship play among tweens (10-13 year olds) on Whyville.net, a tween virtual world populated by over 1.5 million users. Using logfiles and representative case studies among 595 players, three levels of quantitative and qualitative analyses were conducted. First, frequency analyses of participation across all realms of play within Whyville identified social gameplay (e.g., chat, email, and social activities) and avatar construction among the top 4 (of 13) categories of play. Second, cluster analyses grouped players into Peripheral Gamers (59%), Semi-Core Gamers (34%) and Core Gamers (7%) based on their pattern of participation among all categories of Whyville, which included social, economic, information seeking, and gaming activities. The third level of analyses delved into the exploration of relationship play using representative case studies from each cluster. These analyses revealed that players were open with their willingness to experiment with virtual flirting (e.g., throwing objects/projectiles, buying gifts, dancing, making out), dat- ing, and engaging in multiple (often brief) relationships. The findings suggest that tweens are actively exploring and experimenting with social and relationship play online.