This article illustrates the value of large-scale impact evaluations with counterfactual components. It begins by exploring the limitations of small-scale impact studies, which do not allow reliable inference to a wider population or which do not use valid comparison groups. The paper then describes the design features of a recent large-scale…

Recognizing that standardized instructional treatments may not be equally effective across contexts, a growing number of scholars are arguing that the strategy of adopting packaged programs and striving to implement them faithfully is neither realistic nor desirable. An alternative view is that scaling up educational treatments requires balancing…