The study looked at the impact of the HighScope curriculum and its professional development training on one group of First Class Pre-K programs, compared to programs doing “business as usual” that had not received the HighScope materials and training. This brief focuses on the impact of HighScope on classroom quality and addresses the following research question: Do teachers in Pre-K programs that adopt the HighScope curriculum exhibit higher quality classroom characteristics (i.e., instructional support, emotional support, and classroom organization) than those in control programs? (author abstract)