Several links between aspects of executive functioning and the development of social competence have been established. The present study investigates the relation between executive inhibitory control and cooperative/non-cooperative behavior, in an ecological setting, and from a longitudinal perspective. Elementary school children (n = 195) of three age groups (7, 9, 11 years, initially) were measured at two consecutive time points, at a one-year interval, with tasks tapping executive inhibitory control (the Stroop test), and social competence (a collaborative puzzle solving task). Executive inhibition was identified as the most influential stable predictor only in the case of non-cooperative behavior and presented strong concurrent relations with both cooperative and non-cooperative behavior at follow-up, even when controlling for previous level of the same behavior. The findings imply the need to consider the important role of executive inhibitory processes in multifactorial models of social competence development and in the refinement of present interventions.