Purpose: to analyze the relevance of family engagement in the implementation of the Picture Exchange Communication System (PECS) in children presented with Autism Spectrum Disorder (ASD). Methods: a longitudinal study with a sample of 22 mother- child dyads with ASD; 17 boys and 5 girls, with a mean age of 7 years and 2 months. The Executor Skills Protocol was used. The PECS implementation program consisted of 24 therapy sessions with the active presence of mothers. The family's support was measured by the frequency of the sessions. Spearman's correlation test and a significance level of 0.05% were used. Results: mothers performed most tasks correctly in the first three phases. There was a tendency to correlation between the executor´s skills and the number of sessions in all phases of the program, and in the four initial phases, the indexes showed a statistical significance. Family compliance was 96%. Conclusion: family engagement was relevant for the appropriation of children to the PECS during the time of exposure, reaching phases of discrimination and construction of sentences with cards.