Classroom emotional climate was hypothesized to moderate psychosocial adjustment in 1st grade for children with an early childhood history of anxious solitude. Participants were 1,364 children in the National Institute of Child Health and Human Development (NICHD) Study of Early Child Care and their mothers, child-care providers, and teachers. As anticipated, children with an early childhood history of anxious solitude were more rejected, poorly accepted (boys), and victimized (girls) by peers and demonstrated more depressive symptoms (girls) in 1st-grade classrooms with negative observed emotional climate. Results support a Child x Environment model of children's social and emotional adjustment.