Objectives: Explore learning processes associated with a psychoeducational pain selfmanagement intervention. Background: Self-management of cancer pain is challenging for patients and their family caregivers (FCs). While psychoeducational interventions can support them to handle these tasks, it remains unclear how learning processes are hampered or facilitated. Methods: A convergent parallel mixed methods design with qualitative data collection embedded in a randomized controlled trial (RCT) was used. Outpatients with cancer and FCs were recruited from three Swiss university hospitals. The six-week intervention consisted of education, skills building, and nurse coaching. Quantitative data on pain management knowledge and self-efficacy were analyzed using multilevel models. Patients and FCs were interviewed post-RCT regarding their learning experiences. Qualitative data analysis was guided by interpretive description. Finally, quantitative and qualitative data were integrated using case level comparisons and a meta-matrix. Results: Twenty-one patients and seven FCs completed this study. The group-by-time effect showed increases in knowledge (p = 0.035) and self-efficacy (p = 0.007). Patients' and FCs' learning through experience was supported by an intervention nurse, who was perceived as competent and trustworthy. After the study, most intervention group participants felt more confident to implement pain self-management. Finally, data integration showed that declining health hampered some patients' pain self-management. Conclusions: Competent and trustworthy nurses can support patients' and FCs' pain self-management by providing individualized interventions. Using a diary, jointly reflecting on the documented experiences, and addressing knowledge deficits and misconceptions through the use of academic detailing can facilitate patients' and FCs' learning of critical skills.