The potential to reduce the morbidity and mortality from colorectal cancer, the second most common cause of cancer death in the U.S. has been compromised because only about half of eligible patients have been appropriately screened. Patients contribute to inadequate colorectal cancer screening by failing to complete ordered tests. Several studies have reported low rates of attendance to scheduled sigmoidoscopy and colonoscopy studies. Because physicians offer limited counseling when ordering these tests, approaches are needed to address patient concerns and to promote adherence to scheduled colon studies. Therefore, we conducted a trial of a theory-based telephone intervention by patient ‘peer coach’ who was trained to address barriers to colonoscopy attendance versus a mailed professional brochure. The support was targeted to those at greatest risk of non-attendance.