The theme of this special issue is timely as the world becomes increasingly flat and globally connected (Friedman, 2007). By focusing on an international perspective in problem-based learning (PBL), it puts culture squarely in the center, whether it is a national or disciplinary culture. The articles in this special issue represent Thailand, South Africa, the Netherlands, the United Kingdom, and the United States. They represent disciplines that include engineering, business, hotel administration, social studies, and sport and exercise physiology. Student populations range from secondary school to postgraduate. It is clear from this collection that PBL serves diverse student populations who have differing needs. Some of the articles discuss the challenges that learners face, in particular, learning to do PBL, whether a result of prior knowledge, language, or experiences in schooling. A consistent theme throughout the special issue is that there are different models of PBL adapted to their local contexts and cultures. Together, this set of papers demonstrates that PBL is being used in a wide range of disciplines by an international PBL community. The two big themes that jump out of this special issue are the need to adapt to local contexts, whether that is cultural or disciplinary contexts (e.g., Hallinger and Lu, this issue; Henry et al., this issue; Summers & Dickinson, this issue). Some of these adaptations have included lectures-so this begs the question as to whether these are appropriately placed just-in-time information resources or whether they are undermining some of the goals of PBL as in the Henry et al. study-creating what Brown and Campione (1996) have called "lethal mutations." Further research is needed to understand the tradeoffs in different adaptations of PBL to understand which ones are pragmatically useful and productive, which ones may pit one goal against another (e.g., sacrificing self-directed learning goals as a tradeoff for more efficiency in content coverage), and which ones no longer seem to be PBL. In some sense, these can be helpful in identifying a hard boundary, if indeed one exists (and they often don't, as found in Hmelo-Silver, Duncan, & Chinn, 2007). Another theme that permeated these studies was a notion of distributed scaffolding (Puntambekar & Kolodner, 2005). The facilitator provides one important source of scaffolding, but several of these studies used other scaffolds as well-through structuring the problem, providing worksheets, creating concept maps (e.g., the Zwaal & Otting study), or encouraging multiple perspectives (as in Smith & Cook study's use of the Six Thinking Hats). Distributed scaffolding is particularly useful in thinking about how technology might play a role in PBL (e.g., Bridges, Botelho, & Tsang, 2010; Hmelo-Silver et al., 2009), particularly in extending the human facilitator as PBL is scaled to larger groups. A word of caution is a need to see both sides of the elephant as educators try to understand how these adaptations and scaffolds help deal with the challenges in enacting PBL in diverse environments. To accomplish that, this community needs mixed methods that help understand not only what students learn, but how students learn and how facilitators use these new models and tools.