A study examined structural determinants of opinion expression by merging two theoretical perspectives: the "spiral of silence" model advanced by Elisabeth Noelle-Neumann, and the structural approach to communication research offered by Phillip Tichenor, George Donohue, and Clarice Olien. The study also distinguished between different forms of opinion expression in terms of: 1) the degree to which the expression is public, and 2) the degree to which feedback is immediate and potentially hostile. Subjects, 478 mass communications students at a midwestern university, were asked their opinions on two social issues, the banning of pornography and the passage of a mandatory seat-belt law. They were also asked about their perceptions of majority opinion in their hometowns and their willingness to express their opinions on these two topics in their hometowns. Results showed significant differences in willingness to express opinion in smaller communities, i.e., those in which the media serve a predominantly distributive function, than in larger, more pluralistic ones, i.e., those in which the media serve more of a feedback function in response to the presence of diverse social and political groups. Specifically, perceived congruity with majority opinion is a significant predictor of two forms of opinion expression in small, but not large, communities. Results suggest that "fear of confrontation" in smaller communities may inhibit opinion expression to a greater extent than the "fear of isolation" mechanism proposed by Noelle-Neumann. (Three figures and 2 tables of data are included; 23 references are attached.) (Author/RAE)