Development of children's vocabularies for gender-typed words and communicative actions was investigated longitudinally from 13 to 36 months and in a group of 9.5-month-olds. Vocabularies of gendered words were assessed using lists of adult-rated gender-typed words from the MacArthur-Bates Communicative Development Inventories (CDI; L. Fenson et al., 1994). At 24 to 36 months, girls' and boys' productive vocabularies contained more same-gender-typed words than other-gender-typed words. Receptive vocabulary gender-differential effects were apparent among boys at 18 months. At 13 and 18 months, gender-typed differences were apparent in communicative actions. The research reveals the utility of unobtrusive, nonexperimental measures for assessing gender-related knowledge and behavior in young children.