Interpersonal citizenship behavior (ICB) in organizations is an inherently relational and multilevel phenomenon. Using a multilevel framework, this study investigates the different levels of social network antecedents of ICBs. Specifically, the authors examine the effects of individual-level network characteristics (centrality and transitivity) and group-level network properties (density and centralization) on individuals’ ICBs. From a sample of 846 individuals in 149 work groups, the authors find that individual centrality and the network density of a group increased group members’ ICBs and note the positive joint effect of both predictors. Furthermore, consistent with their prediction, the tendency for individuals embedded in a local triad to display less ICB is greater in the decentralized group. This result shows a possible trade-off between structural positions in local and global networks in facilitating individuals’ ICBs.