Due to the difficulties in assessing cognition in young toddlers, we rely on attainment of developmental milestones through standardised developmental assessment. We have developed a touchscreen based assessment tool- (the Babyscreen app)- designed to test the cognitive pre-requisites of working memory, processing speed, visual attention, and hence; executive function in children aged 18-36 months. We wished to examine the internal reliability and validity of the app in comparison to validated measures of executive functioning.