Effectiveness and outcomes research seeks to improve patients' health outcomes by improving the quality of the health care they receive. Dissemination of the findings of such research is a necessary step in that process. This paper reviews what is known about designing and disseminating effective information packages aimed at health care providers (mainly physicians), where effectiveness means promoting behavior change on the part of practitioners that leads to better patient care. Practice-relevant research information is delivered to providers through publication of results from randomized clinical trials, dissemination of consensus recommendations, development and use of computer-based aids to clinical decision making, and provision of continuing medical education. Each of these areas offers numerous examples of the exceedingly modest behavioral response that can be expected from the mere provision of information. The literature also offers some principles that may improve the chances for success, including the desirability of techniques that involve face-to-face interaction, promoting the active involvement of the learner, repeating the message, making recommendations explicit and relevant to clinical practice, and making use of opinion leaders and peer influence. Little basic research has been done on providers' motivations and actual decision-making processes. Research aimed at furthering a behavioral science of providers could yield new insights on effective dissemination strategies as well.