Research Findings: The purpose of the present study is to examine the degree to which assistant and lead teachers work together in Head Start classrooms in 3 domains: emotional support, classroom organization, and instructional support. Pairs of lead and assistant teachers from 14 Head Start classrooms were simultaneously observed for 1 morning to examine the quality of teachers' interactions with students in these 3 domains. First we examined the mean levels of the 3 domains and how they differed among teachers. Overall, results indicated moderate levels of emotional support and classroom organization and low levels of instructional support. In comparing lead and assistant teachers, we found that lead teachers offered significantly higher levels of instructional support than assistant teachers. Next we examined how the quality of lead and assistant teachers' interactions were related over time. Concurrent correlations were nonsignificant. Lagged correlations suggested that lead and assistant teachers' interactions with students were related over time. Practice or Policy: Assistant teachers offered comparable levels of emotional support and classroom organization but did not offer the same levels of instructional support. This suggests that assistant teachers are able to help provide a nurturing environment and help with structuring activities despite having lower entry-level qualification requirements. This study supports the notion that assistant teachers as well as lead teachers should be included in quality improvement efforts. (Contains 4 tables.)