A groundbreaking contribution to transaction cost analysis was advanced by John (1984) who recognized that managerial opportunism is a behavioral variable requiring theoretical explanation, not an exogenous constraint to be assumed and imposed upon the marketing channel network. However, it is argued that several features of John's final model predicting opportunism seem problematic. An alternative model, one that explains supplier power and managerial opportunism-the latter being viewed as an aspect of the broader and more common social psychological construct of compliance-is proposed and operationalized using John's (1984) indicator measures. Then, using John's (1984) published data, this model is subjected to statistical testing and modification through analysis of covariance structures. Results suggest that the proposed model is superior to John's with respect to goodness-of-fit and other important modeling criteria. Conclusions, managerial implications, study limitations, and directions for future research are discussed.