The study reported was part of a large thinking skills intervention for 11–12-year-old children. This paper focuses on the impact of a thinking skills intervention on children's understandings of intelligence. A total of 178 children (n = 86 girls and n = 92 boys) across six schools participated in the study. Children were individually pre-tested in the classroom using written tasks designed to tap concepts of intelligence (definitions, characteristics, causes of intelligence, and the stability of intelligence: entity versus incremental concepts) and a variety of thinking skills. Schools were allocated into one of three intervention conditions: control condition; individual condition; collaborative learning condition. Children in the individual and collaborative learning conditions participated in an 8-week thinking skills intervention. Children in the individual condition worked individually on tasks to apply the thinking skills whereas learners in the collaborative condition applied the thinking skills on tasks in groups of four. Following the thinking skills intervention all children were individually post-tested using the pre-test measures. The results showed that the intervention had an impact on children's understanding of intelligence. In particular, the collaborative learning intervention led to most improvement in concepts of intelligence. The results are discussed with reference to theories of intelligence concepts and thinking skills interventions.