The first portion of this article describes the development and validation of a classroom observation measure. The goal of the measure was to assess the quality of reading instruction provided to first-grade English learners. We report the internal consistency reliability, interrater reliability, the development of empirically derived subscales, and the criterion-related validity of the subscales. The latter was moderately high for three of the six subscales (range = .62-.65) and moderate for the three others (range = .49-.57). The second portion of this article includes a contrasted groups analysis of the four classes with the lowest and highest growth in reading. We conclude with a presentation of the major themes and issues that emerged in the qualitative field notes.