Autistic students experience greater social difficulties and heightened internalizing behaviors (e.g., anxiety, depression, withdrawal) relative to their nonautistic peers, yet little is known about how these domains influence one another over time. This 1.5-year longitudinal study analyzed the associations between teacher-reported social skills and internalizing behaviors across three time points for 177 autistic students aged 4-7 years. Cross-lagged panel analyses indicated an association between earlier internalizing behaviors and later social skills for autistic students, whereby lower internalizing behaviors predicted greater growth in social skills from one school year to the next. These changes in social skills followed children across multiple teachers and classroom contexts. The opposite cross-lagged path was not supported as early social skills did not predict changes in internalizing behaviors over time. Internalizing behaviors showed similar associations with later social skills for autistic students regardless of cognitive ability, for those in general and special education classrooms, and for those whose teachers did and did not have autism-specific training. Findings suggest that promoting students' early emotional well-being and targeting internalizing behaviors may indirectly enable social development over time. [This is the online version of an article published in "School Psychology" (ISSN 2578-4218).]