Access to high-quality education is uneven, particularly for preschool children who are at risk for school failure. Professional development (PD) for teachers, including the use of coaching, is an increasingly common approach for promoting evidence-based instruction. Existing research suggests that the frequency of teacher participation in a PD intervention is related to the magnitude of PD effects, but there is little research on how to engage teachers in learning about and implementing evidence-based practices. In this article, the authors describe an iterative approach to the development of a PD intervention that employs coaching aimed at helping Head Start teachers improve their language and literacy instruction. The authors describe sequential, small-scale studies that influenced their approach to PD. Results of a pilot study of the PD intervention suggested that teachers had positive responses to the intervention content and approach. Implications for developing and implementing PD interventions designed to improve classroom instruction are included. (Contains 1 table.)