Watchful waiting is a reasonable alternative to treatment for some older men with localized prostate cancer, but it inevitably brings uncertainty. This study tested the effectiveness of the watchful waiting intervention (WWI) in helping men cognitively reframe and manage the uncertainty of watchful waiting. Based on Mishel's Reconceptualized Uncertainty in Illness Theory (Image. 1990; 256–262), the WWI was tested with a convenience sample of 41 men. Experimental subjects received 5 weekly intervention calls from a nurse. Control subjects received usual care. Outcomes were new view of life, mood state, quality of life, and cognitive reframing. Repeated measures of analysis of variance were used to test the effectiveness of the WWI. The sample was 86% Caucasian and 14% African American, with an average age of 75.4 years. Intervention subjects were significantly more likely than controls to view their lives in a new light (P = .02) and experience a decrease in confusion (P = .04) following the intervention. Additionally, intervention subjects reported greater improvement in their quality of life than did controls (P = .01) and believed their quality of life in the future would be better than did controls (P = .01). This study's findings document the benefits of the WWI for patients living with uncertainty.