In this study, we empirically examine the diffusion of enterprise systems (ES) systems, and the influence of competency factors on firm performance. A model, based on systems and innovation diffusion theories, was developed and a survey instrument used to gather data from a sample of production firms to test the hypothesized model relationships. The results of the multivariate analyses indicate that ES subsystem implementation statuses influence firm performance differently, and that competency factors play an important role in augmenting firm performance. The findings suggest that an adopter-subsystem-systemic diffusion and competency-based approach to ES implementations can help firms obtain increased benefits from their deployments.