This study examines sources of individual variation in child vocabulary competence in the context of a multivariate developmental ecological model. Maternal sociodemographic characteristics, personological characteristics, and vocabulary, as well as child gender, social competence, and vocabulary competence were evaluated simultaneously in 126 children aged 1;8 and their mothers. Measures of child vocabulary competence included two measures each of spontaneous speech, experimenter assessments, and maternal reports. Maternal measures, from proximal to distal, included vocabulary, verbal intelligence, personality, attitudes toward parenting, knowledge of parenting, and SES. Structural equation modelling supported several direct unique predictive relations: child gender (girls higher) and social competence as well as maternal attitudes toward parenting predicted child vocabulary competence, and mothersʼ vocabulary predicted child vocabulary comprehension and two measures of mother-reported child vocabulary expression. In addition, childrenʼs vocabulary competence was influenced indirectly by mothersʼ vocabulary, social personality, and knowledge of child development. Maternal vocabulary itself was positively influenced by SES, maternal verbal intelligence, and mothersʼ knowledge about parenting. Individual variation in child vocabulary competence might best be understood as arising within a nexus of contextual factors both proximal and distal to the child.