Research Findings: Social-emotional competence is especially important for children living in poverty, and effective assessment of social-emotional skills is critical. This study examined parent-teacher agreement and reliability of the Devereux Early Childhood Assessment (DECA; P. A. LeBuffe & J. A. Naglieri, 1999) English and Spanish forms in a large (n = 7,756) sample of impoverished, ethnically diverse preschoolers. Both forms were reliable. Parents reported greater social-emotional protective factors and behavioral concerns than teachers. Parent-teacher agreement was moderate (rs = 0.20-0.28) and consistent with previous research. Parent-teacher agreement was higher when both informants completed the survey in the same language. Agreement was highest for average-functioning children, according to a standardized assessment of cognition, language, and motor skills that was also administered. Parents rated low-functioning children more favorably than did teachers; teachers rated high-functioning children more favorably than did parents. Practice or Policy: The English and Spanish DECA forms demonstrate reliability for examining social-emotional skills and behavioral concerns for impoverished, ethnically diverse preschoolers. (Contains 5 tables.)