The effectiveness of the Incredible Years® Teacher Classroom Management program (IY-TCM) in improving children's outcomes has been well-documented. We explored its effectiveness by examining the outcomes of children whose teachers completed the IY-TCM training during the COVID-19 pandemic. Based on a quasi-experimental design, this study involved 28 teachers and 403 preschool children from their classes. Children's social skills and behavior problems were assessed by teachers at three different times. The results showed that, following the intervention, the teachers reported that the children in the IY-TCM group had more social skills and fewer behavior problems than those in the non-intervention group. These improvements, more evident at follow-up, were associated to a decrease in the number of children at-risk for social and behavioral problems. Findings provided further support for the documented benefits of the IY-TCM on children's social and emotional behaviors, while also highlighting its effectiveness even when delivered in challenging conditions.