There is ample evidence that many clinical decisions made by physicians are inconsistent with current and generally accepted evidence. This leads to the underuse of some efficacious diagnostic, preventive or therapeutic services, and the overuse of others of marginal or no value to the patient. Evolving new payment and delivery models place greater emphasis on the provision of evidence-based services at the point of care. However, changing physician clinical behaviors is likely to be difficult and slow. Policy makers therefore need to design interventions that are most effective in promoting greater evidence-based care. To help identify modifiable factors that can influence clinical decisions at the point of care, we present a conceptual model and literature review of physician decision making. We describe the multitude of factors--drawn from different disciplines--that have been shown to influence physician point-of-care decisions. We present a conceptual framework for organizing these factors, dividing them into patient, physician, practice site, physician organization, network, market, and public policy influences. In doing so, we review some of the literature that speak to these factors. We then identify areas where additional research is especially needed, and discuss the challenges and opportunities for health services and policy researchers to gain a better understanding of these factors, particularly those that are potentially modifiable by policymakers and organizational leaders.