Structural, attitudinal, and affective response correlates of four stages in the innovation process were examined in 30 multispecialty medical groups. In these professional organizations, formal hierarchical decision-making and affective responses were significantly related to various stages in the innovation process. Participation by all physicians in strategic decisions was negatively related to each step in the innovation process. By contrast, organization size, complexity, formalization, and person specialization were not related to innovation activity. The authors speculate that minimal "bureaucratization" may be necessary to move the innovation process in differentiated professional groups.