Preschool teachers from a high-poverty, urban school district were trained to implement Story Talk, a book reading intervention designed to increase children's vocabulary and language development using supportive materials and strategic individualized coaching. Thirty-five teachers were randomly assigned by site to the intervention (20) or the…

In experimental studies, researchers are often interested in secondary research questions that explore important aspects of main findings, such as whether or not program effects vary according to the level of fidelity in which the program has been implemented; or according to the dosage received by individuals participated in the program. In this…