This document outlines principles for designing social experiences and interactions. It discusses how people live in networks and are influenced by others. It emphasizes designing systems, not just destinations, to account for these networks. It identifies three key areas of social design: identity, connectedness, and communication. For each area, it provides design principles such as giving privacy controls in context, showing commonalities between loosely connected people, and supporting lightweight interactions to build relationships over time. The overall message is that social design must consider how people are shaped by and engage with their complex social networks.