The study aims to provide high quality evidence on the second most used assessment tool in Head Start--the Preschool Child Observation Record, 2nd edition (COR-2). To that end, this study has five objectives: (1) determine the dimensionality of the COR-2; (2) determine whether or not the optimal factor structure is the same for boys, girls, Whites, African Americans, Latinos, English language learners, and across time; (3) assess the extent to which the COR-2 is related to other validated measures of development captured at the same time and in the future; and (4) test the assumption that the five skill points of each COR-2 item are in fact in order of skill complexity. The study analyzes a subset of data from the Evidence-Based Program for the Integration of Curricula (EPIC) project, a comprehensive early childhood program specifically designed for preschool children from an underserved, minority urban population. This study uses the COR-2 data collected from a large representative sample of preschool children from low income households to examine the validity and quality of the COR-2 to inform child care services using rigorous psychometric methods. The project will interpret the research findings collaboratively with policymakers, child care professionals, and parents to stimulate a discussion about purposeful assessment in early childhood and to determine ways to improve assessment for preschool children from low income households.