There are a growing number of problem-based learning (PBL) studies in virtual worlds (VWs); however, the suitability of these approaches is still unknown for particular knowledge domains and in full-time courses. In this paper, we argue that VWs can support a constructionist approach to PBL for blended-practice-based courses of design and engineering, and we describe an instructional design framework and its application at an HCI (human–computer interaction) design course. The approach places emphasis on learning by doing, and enables students to collaboratively work in authentic and ill-defined situations, follow self-directed routes to address problems, and construct digital artifacts as candidate solutions. The proposed approach translates the principles of PBL into guidelines for setting up a VW as a learning environment, building supporting tools, and implementing learning activities that require that students create digital models that reflect their understanding about their learning. We have applied the framework in a blended postgraduate course in HCI design that involved various PBL activities and the application of methods related to the lifecycle of interactive product development (including user research, conceptual design, prototyping, and usability evaluation). The results were encouraging with respect to the applicability of the approach, students' acceptance, as well as perceived usability of the VW environment and tools in the long term.