Spiral of silence theory does not assume a simple relationship between opinion climate and opinion expression. In fact, the notion of hardcore individuals (who express their opinions regardless of the climate) embraces the idea that there are some people for whom this relationship does not hold true. However, this idea has not been put to a direct empirical test. In this article, the authors propose that attitude certainty is a key variable in identifying the hardcore. Data from three surveys demonstrate that the climate of opinion only determines opinion expression when individuals hold their attitudes with low or moderate attitude certainty. For individuals with high attitude certainty, no such effect can be found. Thus, there is a spiral of silence only for some but not for all members of the public.