Within the vast and rich field of online gaming, a new generation of Online Social Games (OSGs) is emerging that have in common a core of social interaction, sometimes explicit, other times implicit. This common core of social experience promises to become at least as important as the experience derived from the game-world itself. In this chapter, we consider the social side of OSGs and provide the following contributions: 1. We motivate the importance of taking social features into account to improve the quality of experience in online gaming. 2. We discuss the various dimensions of (player experience in) OSGs. 3. We describe a social network analysis methodology for identifying relations in OSGs and indicate how this methodology could be used to improve the game-play experience. 4. We also consider and illustrate how certain "social" behaviour, like toxicity, is negative and may harm the game-play experience, if not adequately addressed. 5. We mention several directions for future research to put the power of social features in OSGs to good use.