Problem- and project-based learning (PPBL) courses in sustainability address real-world sustainability problems. They are considered powerful educational settings for building students’ sustainability expertise. In practice, however, these courses often fail to fully incorporate sustainability competencies, participatory research education, and experiential learning. Only few studies exist that compare and appraise PPBL courses internationally against a synthesized body of the literature to create an evidence base for designing PPBL courses. This article introduces a framework for PPBL courses in sustainability and reviews PPBL practice in six programs around the world (Europe, North America, Australia). Data was collected through semi-structured qualitative interviews with course instructors and program officers, as well as document analysis. Findings indicate that the reviewed PPBL courses are of high quality and carefully designed. Each PPBL course features innovative approaches to partnerships between the university and private organizations, extended peer-review, and the role of knowledge brokers. Yet, the findings also indicate weaknesses including paucity of critical learning objectives, solution-oriented research methodology, and follow-up research on implementation. Through the comparative design, the study reveals improvement strategies for the identified challenges and provides guidance for design and redesign of PPBL courses.