A large number of studies have been devoted to the impact of perceptions of opinion distributions on the expression of public opinion. In the present study we propose that perceptions of opinion distributions have implications that go beyond influencing individual issue stances, but rather influence respondents' willingness to engage in political activities. Specifically, we examine the link between opinion perceptions and two dimensions of political participation: participatory behavior involving public expression of opinion, and participatory behavior that does not involve the public expression of a person's opinion. Based on data collected as part of the 1996 American National Election Study, we examine the role that communication variables, group membership, attitude strength, and perceptions of public opinion play in predicting public and non-public forms of participation in the US. Implications for research in the areas of political participation and public opinion expression are outlined.