Methods: A nested concurrent mixed methods design will be used for this multi-center study, that is, an RCT will be combined with a qualitative substudy. Participants will complete a baseline evaluation, after which they will be randomly assigned to a 6-week intervention or usual care group. Blinding of data collectors is not feasible. Participants in both groups will complete a daily pain and symptom diary; other outcomes will be evaluated at 6 weeks post-randomization. The primary outcome of this study will be average and worst pain intensity. A total sample of 210 patients with cancer pain and approximately 105 FCs will be recruited from the oncology outpatient clinics of the University Hospitals Basel, Zurich and Bern. The intervention is designed to implement structured and tailored components (information, skill-building, nurse coaching) of the German PRO-SELF© Plus PCP. Participants will receive weekly in-home or telephone visits. Data analysis will follow an intent-to-treat strategy and generalized mixed models will be used. Average per-patient costs for the intervention will be calculated. For the qualitative substudy, approximately 7-10 patients and FCs per group and site will be interviewed regarding their experiences with pain management and intervention. Interpretive description will be used, including stepwise, systematic and iterative processing of data, leading to a meaningful description and interpretation.