Background: Despite poor school performance by adolescents in secure residential care and the potential importance of education during care, little is known about how to achieve academic success with these adolescents. Objective: Therefore, the aim of the present study is to assess adolescents' academic achievement during secure residential care and to identify factors that are associated with adolescents' achievement. Methods: In the present study, we have included a sample of 53 adolescents in secure residential care using information from the individual care plans, the adolescents themselves, and their teachers. Results: Contrary to our expectations, teachers report an average-to-good school performance for a majority of the adolescents (53.8%). Partly consistent with our expectations, students with an average intelligence level, good academic motivation, and/or relatively few externalizing behavioral problems show significantly better academic achievement than students with a low intelligence level, poor academic motivation, and/or many externalizing problems. The results also suggest that low intelligence and poor motivation predict academic achievement, both directly and indirectly, through an increased risk for externalizing problems. Unexpectedly, we did not find significant associations between teachers' interaction skills, student-teacher relationship quality, and adolescents' academic achievement. Conclusions: Considering our findings, future research should aim at interventions that focus on improving teachers' ability to handle poor academic motivation and externalizing behavioral problems.