In a randomized controlled design, this study tested the efficacy of a theoretically based uncertainty management intervention delivered to older long-term breast cancer survivors. The sample included 509 recurrence-free women (360 Caucasian, 149 African–American women) with a mean age of 64 years (S.D.=8.9 years) who were 5–9 years post-treated for breast cancer. Women were randomly assigned to either the intervention or usual care control condition. The intervention was delivered during four weekly telephone sessions, in which study nurses guided cancer survivors in the use of audiotaped cognitive–behavioral strategies to manage uncertainty about recurrence, and a self-help manual designed to help women understand and manage long-term treatment side effects and other symptoms. Treatment outcome data on uncertainty management were gathered at pre-intervention and 10-months afterward. Repeated measures MANOVA evaluating treatment group, ethnic group, and treatment by ethnic interaction effects indicated that training in uncertainty management resulted in improvements in cognitive reframing, cancer knowledge, patient–health care provider communication, and a variety of coping skills. Results are discussed in terms of the importance of theory-based interventions for cancer survivors that target triggers of uncertainty about recurrence and in terms of ethnic differences in response to the intervention. Copyright © 2005 John Wiley & Sons, Ltd.