Background: To preserve quality and continuity of care, collaboration between primary-care and secondary-care physicians is becoming increasingly important. Therefore, learning intraprofessional collaboration (intraPC) requires explicit attention during postgraduate training. Hospital placements provide opportunities for intraPC learning, but these opportunities require interventions to support and enhance such learning. Design-Principles guide the design and development of educational activities when theory-driven Design-Principles are tailored into contextsensitive Design-Principles. The aim of this study was to develop and substantiate a set of theory-driven and context-sensitive Design-Principles for intraPC learning during hospital placements. Methods: Based on our earlier research, we formulated nine theory-driven Design-Principles. To enrich, refine and consolidate these principles, three focus group sessions with stakeholders were conducted using a Modified Nominal Group Technique. Next, two work conferences were conducted to test the feasibility and applicability of the Design-Principles for developing intraPC educational activities and to sharpen the principles into a final set of Design-Principles. Results: The theoretical Design-Principles were discussed and modified iteratively. Two new Design-Principles were added during focus group 1, and one more Design-Principle was added during focus group 2. The Design-Principles were categorised into three clusters: (i) Culture: building collaborative relations in a psychologically safe context where patterns or feelings of power dynamics between primary and secondary care physicians can be discussed; (ii) Connecting Contexts: making residents and supervisors mutually understand each other's work contexts and activities; and(iii) Making the Implicit Explicit: having supervising teams act as role models demonstrating intraPC and continuously pursuing improvement in intraPC to make intraPC explicit. Participants were unanimous in their view that the Design-Principles in the Culture cluster were prerequisites to facilitate intraPC learning.