Multidimensional empirical examinations of the adoption of innovations in organizations, and the influence of factors within each dimension on the phases of adoption, are scarce. This study examines the effects of environmental, organizational and top managers' characteristics on the initiation, adoption decision and implementation of innovation. Using a sample of approximately 1200 public organizations in the United States, we found that while each dimension accounts for unique variance in the adoption of innovation, organizational characteristics and top managers' attitudes toward innovation have a stronger influence than environmental and top managers' demographic characteristics. We also found no difference in the direction of effects of any antecedent, but did find differences in the significance of effects of several antecedents, on the phases of innovation adoption. We discuss the implications of these findings and suggest ideas for future research.