Although scaffolding is an important and frequently studied concept, much discussion exists with regard to its conceptualizations, appearances, and effectiveness. Departing from the last decade's scaffolding literature, this review scrutinizes these three areas of scaffolding. First, contingency, fading, and transfer of responsibility are discerned in this review as the three key characteristics of scaffolding. Second, an overview is presented of the numerous descriptive studies that provided narratives on the appearances of scaffolding and classifications of scaffolding strategies. These strategies are synthesized into a framework for analysis, distinguishing between scaffolding means and intentions. Third, the small number of effectiveness studies available is discussed and the results suggest that scaffolding is effective. However, more research is needed. The main challenge in scaffolding research appears to be its measurement. Based on the encountered and described measurement problems, suggestions for future research are made. © 2010 The Author(s).