Background: Pain self-management support interventions were effective in controlled clinical trials and meta analyses. However, implementation of these complex interventions may not translate into identical effects. This paper evaluates the implementation of ANtiPain, a cancer pain self-management support intervention in routine clinical practice according to the Reach Efficacy-Adoption Implementation Maintenance framework. Methods: In this cluster randomized study with a stepped wedge design, N = 153 adult patients with cancerrelated pain were recruited from 01/17 to 05/18 on 17 wards of 3 hospitals in Vienna, Austria. ANtiPain entailed a face-to-face in-hospital session by a trained nurse to prepare discharge according to key strategies, information on pain self-management, and skills building. After discharge, cancer-pain self-management was coached via phone calls. Patient-level data were collected at recruitment, and 2, 4 and 8 weeks after discharge via postal or online questionnaire. Primary outcome was pain interference with daily activities. Secondary outcomes included pain intensity, self-efficacy, and patient satisfaction. Organizational-level data (e.g., on implementation procedures) were collected by study or intervention nurses. The mixed model to analyze patient-level data included a random intercept and a random slope for individual and a random intercept for ward.