The dominant paradigm in political participation studies largely ignores the microcontexts within which citizens are embedded. Drawing on generic processes of persuasion and selection, this study specifies six testable research hypotheses about individuals' attitudes and behaviors as consequences of the form and content of their ego-centric networks. Using the network measures from the 1987 General Social Survey, respondents'perceptions of their egocentric networks are found to predict involvement in national elections. The more frequently people discuss political matters with their intimates, the greater their interest and participation in national campaigns and voting. The partisan composition of the network strongly influences their participation, even after controlling for party identifications and selection effects of social attributes. However, respondents' closeness to network others has few substantial effects, and most of the interaction terms are not significant. For members of voluntary associations, having at least one other with whom they frequently discuss politics strongly boosts mobilization in internal organizational affairs and in the local community, again controlling for social attributes.