The aim of this study was to analyze the relationship between effortful control and language performance, and the mediation effect of sociometric status on this relationship. The sample comprised 472 Spanish children 6-8 years old. To measure temperament, the parents were given the Temperament in Middle Childhood Questionnaire (TMCQ). The nomination method was used in the classroom context to measure social acceptance and rejection, whereas language performance was reported by the teachers at the end of the academic year. The results confirmed the positive relationship between effortful control and language performance. By using a causal mediation analysis, we found a mediation effect for both variables, which confirms the significant effect of self-regulatory skills on the integration of children in their group, and this social adjustment / maladjustment being what determines language performance.