Objective Treatment for localized prostate carcinoma (PCa) is frequently associated with decrements in sexual functioning and satisfaction. Given the highly interpersonal nature of these decrements, interpersonal problems (such as interpersonal sensitivity) may affect recovery of sexual functioning after PCa treatment through interference with physician and partner communication and through distorted cognitions surrounding sexual dysfunction. The objective of the present study was to determine the effect of interpersonal sensitivity on several treatment indicators, including response to a group-based psychosocial intervention. Methods Participants were 101 older men recovering from radical prostatectomy who were enrolled in a randomized controlled trial of a 10-week group-based cognitive–behavioral stress management (CBSM) intervention. Measures included the Inventory of Interpersonal Problems and the sexual functioning subscale of the University of California-Los Angeles quality-of-life measure. Results At baseline, interpersonal sensitivity was related to a belief linking sexual dysfunction to core male identity (r=.29, P<.05). Using hierarchical regression, we found that (a) the CBSM intervention was effective in promoting sexual recovery in all participants, and (b) this effect was moderated by interpersonal sensitivity, such that individuals with higher levels of interpersonal sensitivity made larger improvements in sexual functioning in response to CBSM. Conclusions CBSM was effective in improving sexual function after radical prostatectomy. Individuals with higher levels of interpersonal sensitivity were more likely to perceive sexual dysfunction as a threat to masculine identity and made larger gains in the CBSM intervention. Results and relevance to the older male cancer patients are discussed from the perspective of interpersonal theory.