Community organization has been viewed as a promising approach to changing preventive behaviors. We evaluated the impact of community organization strategies to promote breast cancer screening ordering by primary care physicians in Washington State. Physicians practicing in two intervention and two control communities were surveyed by mail pre-intervention (1989) and post-intervention (1993). Intervention activities targeting the health care sector included the formation of local physician planning groups, a series of informational mailings, medical office staff training sessions, and reminder system support. There were no significant post-intervention differences in the self-reported mammography ordering of physicians practicing in the intervention and control areas. Over the four-year study period, the proportions of physicians who ordered regular mammography increased by 36%. By 1993, over 80% of the respondents routinely used mammographic screening. Concerns about the high price of mammograms and inadequate insurance coverage were significantly reduced over time in both community pairs. Also, use of patient reminder systems increased significantly between 1989 and 1993. Secular trends resulting from diffusion of strategies to promote mammography were responsible for increases in physician ordering of the procedure. Year 2000 goals for breast cancer screening use by physicians may already have been met in some communities.