This study reports an independent investigation of the psychometric properties of Desired Results Developmental Profile (DRDP), a teacher-rated measure of school readiness for preschool-aged children. In a sample of 2,031 low-income, 3- to 5-year-old children attending Head Start, we tested three measurement models: a higher order one-factor model, a seven-factor model, and a five-factor model. To explore the appropriateness of the DRDP for use with diverse populations of young children, we used multiple group and differential item functioning (DIF) analyses to determine whether the DRDP works differently for dual language learners (DLL) and non-DLLs. The proposed five-factor structure fits the data best, with greater face and statistical validity. Using this conceptually driven factor structure, the multiple group analyses were robust for DLL and non-DLL preschool students. More than half of the items on the DRDP displayed little DIF. Items measuring emergent language and literacy exhibited DIF favoring non-DLL children. [For the Grantee Submission, see ED596379.]