Several explanations of social movements rest on the assumption that participants are bonded together by a commonly-held set of beliefs differentiating them from non-participants. This is especially true of Smelser's theory of collective behavior and its central concept, the generalized belief. Components of the generalized belief are examined in light of recent studies of groups within the environmental movement; results disclose significant heterogeneity, especially regarding responsibility for environmental problems and visions of solutions. Data from a total census of a focal group within one urban environmental coalition are presented and the distribution of beliefs across its structure described. The degree of homogeneity of beliefs decreases with movement from the center to the periphery of the group. These analyses suggest that collective action by social movement organizations results from emergent internal processes and structures rather than initial consensus among movement participants.