Dataset & Codebook for the study titled 'The impact of Anxiety on Executive Functions and Academic Performance in children and adolescents' (Gers, Jablonka & Altgassen) Research suggests that symptoms of anxiety directly impact executive functioning, causing a lack of inhibitory control and working memory deficiencies, which may in turn be responsible for a lack of academic success. This study explores a mediating influence of executive functions in the relationship between internalizing symptoms and academic performance. Sixty-two children (8-10 years) and seventy-two adolescents (14-16 years) were recruited from German schools and youth centres. Participants completed executive function tasks testing working memory and inhibitory control and the State and Trait Anxiety Inventory. Academic performance was assessed with tests of reading fluency and competence. Most recent grades in Maths and German were further included in the analysis of academic success.