Colorectal cancer (CRC) screening in the Medicare population remains low despite Medicare coverage. We describe a population-based effort to increase CRC testing of Medicare enrollees in two States through promotion and distribution of office-based tools to primary care physicians and gastroenterologists. Small increases in colonoscopy test use by primary care physicians were observed, but the differences were not statistically significant. Results in one State were stronger than the other, and two components of the intervention appeared more promising than others. Use of CRC tests can be increased, but additional approaches are needed.