The purpose of this study is to investigate the effects of providing early care and education (ECE) teachers with written, individualized, instructional feedback on a variety of child, teacher, and provider-level outcomes. This study exploits the random selection process for selecting teachers to receive classroom observations and written feedback as part of the Ohio Department of Education (ODE) Early Language and Literacy Classroom Observation (ELLCO) project to identify these effects using available statewide data. As policy makers and states and local ECE agencies determine how to improve quality and effectively use the available financial resources, it is important to understand the effectiveness of particular quality improvement efforts that can be implemented at scale.