Background Scientifically based measures are key to monitoring and advancing students’ learning. The use of such assessments has been called for in national legislation 1 and locally in the District’s Action Plan. To help meet these calls, this study investigated the validity of one of the most widely-used early childhood measures: the Preschool Child Observation Record, 2 nd ed. (COR-2). 2 The COR-2 has 32 items organized into six categories: Initiative, Social Relations, Creative Representation, Movement and Music, Language and Literacy, and Math and Science. Each item has five skill points that aim to capture a developmental sequence. Project Overview Despite its widespread use, there is no independent research on the COR-2. This study helps to bridge this knowledge gap by investigating the following research questions: RQ 1. Does the COR-2 capture six factors corresponding to its six categories? RQ 2. What is the empirically derived factor structure of the COR-2? RQ 3. Do the five skill points of each item represent a developmental sequence? Methods Data came from administrative records on all children enrolled in the District’s Head Start program in RQ 1. The six categories were evaluated with confirmatory factor analysis. This analysis was replicated with data from all non-Head Start programs to test the results’ generalizability. RQ 2. Exploratory and confirmatory factor analyses were conducted to empirically uncover the factor structure. RQ 3. Item response theory was used to examine the extent to which each item’s skill points represented a developmental sequence. Results/Conclusions RQ 1: The six factors did not fit the data well and were highly correlated (.85–.97), calling into question their distinctiveness. This result was replicated with non-Head Start programs. RQ 2: Four factors fit the data better than six, but the factors were still highly correlated and explained only a small amount of the variability. RQ 3: Problems were found with the functioning of a third of the items’ skill points. Conclusion: Further development of the COR-2’s constructs and items is needed. Research to Practice Strategies Key points for the Action Plan’s call for a rigorous assessment system: 1.The validation process used here can be used to evaluate potential measures. 2.Adequate assessment training is needed to ensure validity and reliability. 1 Head Start Act as amended 2007, 42 USC 9801 et seq. 2 HighScope Educational Research Foundation. (2003). Preschool Child Observation Record, 2nd ed. Ypsilanti, MI: HighScope Press. * This research was supported by IES and a Child Care Research Scholars Grant from OPRE, ACF, DHHS. This work is the authors’ sole responsibility and does not necessarily represent views of the supporting agencies. Validation of the Preschool Child Observation Record Contact Information Name: Katie Barghaus & John Fantuzzo Organization: University of Pennsylvania Phone Number: Address: