Twenty-six Head Start preschool classrooms participated in a yearlong intervention designed to link the Head Start Child Outcomes Framework with authentic assessment practices. Teachers in intervention and pilot classrooms implemented an assessment approach that incorporated the use of a curriculum-based assessment tool, the development of portfolios aligned with the mandated Head Start Child Outcomes, and the integration of this child assessment information into individual and classroom instructional planning. During the intervention period, comparison classrooms continued to use the assessment approach adopted by the local Head Start program, which included the use of a standardized assessment tool and the use of an agency-developed lesson plan form. Intervention and pilot classrooms demonstrated significant improvements on some dimensions of classroom quality as measured by the Early Language and Literacy Classroom Observation (ELLCO) toolkit, whereas comparison classrooms exhibited no change in classroom quality. Implications for practice are discussed.