There is converging evidence on the strong relationship between working memory capacity and mathematical performance. Test anxiety is a potential moderating factor involved in the relationship between working memory and academic performance. Based on Eysenck and Calvo’s (1992) Processing Efficiency Theory the present study investigated whether associations between working memory and educational achievement in mathematics were moderated by test anxiety. 624 children aged 9-10 years completed verbal, spatial, and complex working memory tasks. Test anxiety was measured using the Children’s Test Anxiety Scale (Wren & Benson, 2004). Mathematical performance was assessed using the Swedish national test in mathematics.