Educational practices that prove effective often involve a substantial investment of training and support time. Unfortunately, that is the very characteristic that makes it difficult and costly to expand the programs on a large scale. A key challenge when scaling up is to maintain high levels of effectiveness at an affordable cost. Assessment-to-Instruction (A2i) is a data-driven professional support system that helps teachers tailor instruction for each child. When delivered with intensive in-person training, it is effective at improving students' reading ability. This Issue Focus introduces the evaluation of a delivery model that uses technology to make the system more affordable.