This randomized controlled trial compared the efficacy of cognitive behavioral stress management (CBSM) and positive psychotherapy in cancer (PPC) to reduce post-traumatic stress symptoms (PTSS) and distress, and to promote post-traumatic growth (PTG) in cancer survivors. Participants were 140 adult women randomly allocated to CBSM (n = 73) or PPC (n = 67). PTSS, distress, and PTG were assessed at pre-and post-intervention, and at 3-and 12-month follow-ups. Analysis showed PPC was more effective in decreasing PTSS (b = −7.61, p <.001) and distress (b = −3.66; p <.001) than CBSM, but neither therapy significantly increased PTG (b = 0.77, p = .76). The relational veracity of PTG and its role predicting reduced PTSS was observed only in the PPC arm. In conclusion, PPC appears to be a valid therapeutic option for assimilating and accommodating the experience of cancer after treatment completion.