This study investigated the moderating effect of gender on the causal relationships between different school play activities (pretend and non-pretend play) and social competence in peer interactions among a sample of Hong Kong children. Participants were 60 Hong Kong preschoolers (mean age = 5.44, 36.67% female). Children with matched home pretend play time period were randomly assigned to pretend or non-pretend play groups to take part in pretend or non-pretend play activities respectively in the 1-month kindergarten play training. Children's pre- and post-training social competences were assessed by their teachers. Results revealed a trend that girls who participated in school pretend play tended to be less disruptive during peer interactions after the training than those who participated in non-pretend play, while boys were similarly benefited from the two play activities. The implications for play-related research and children's social competence development are discussed.