Churn refers to loss of customers and understanding churn behavior and being able to accurately predict likely churners is important for any business as it directly affects the customer base and thus revenue. Analysis of churn behavior is also important in terms of understanding factors of user engagement. As such, churn behavior has been studied across a wide range of industries such as telecom, banking and online social networks. However, most of existing churn research has focused on modeling individual churn behavior and the type of questions has also been limited by the types of datasets which are available to researchers. In this thesis, different aspects of churn in a Massively Multiplayer Online Role Playing Games (MMORPGs) are studied in depth. MMORPGs are persistent virtual environments that mimic complex physical spaces and many of the behaviors which are observed in the real world are also observed in MMORPGs. Millions of players interact in an online manner in these environments and the game logs capture player activities in great detail. We first use a behavior modeling approach to analyze the player's behavior leading up to the point of churn and discover key indicators or behavioral trends which can help identify players who are going to churn. We do an extensive evaluation and comparison of two types of churn - Cancellation of Subscription and Dormancy, using this approach. MMORPG environments are characterized by collaboration among players to achieve common goals in activities such as raids and group quests. We identify player communities which evolve over time in such game environments and extend the lifecycle -based approach to build models for predicting churn of these dynamically evolving communities. Models of player motivation seek to identify factors that motivate player behavior and can be helpful in analyzing and predicting churn behavior. We study the impact of different achievement and socialization-based player motivational factors on player churn. Specifically, we are interested in studying how socialization serves to increase player engagement and decrease churn. Contagion processes arise broadly in the social and biological sciences and can be seen in, for example, the spread of infectious diseases, the diffusion of innovations, dissemination of religious doctrine and information diffusion in online social networks. As per theories of social contagion, behavior and emotions can be transmitted between individuals in a population. We study the relationship between player churn and social contagion i.e when a player leaves a network, what is the impact on its immediate neighborhood. All of the existing churn research have focused on factors which lead to churn. We study the interpersonal effects which can cause spread of churn behavior in a network as well as the factors which keep a player in the network after his neighbor has churned.