The current study brought a bioecological approach to children’s early vocabulary development using data from the Longitudinal Study of Australian Children. Relevant data were available for 2188 children (1119 male) who had a median age of 9 months (M = 9.3 months, SD = 2.1 months) at Wave 1 and a median age of 34 months (M = 34.2 months, SD = 2.5 months) at Wave 2. Results support the developmental importance of joint attention and parent-child book reading as well as the argument that the effects of individual (e.g., parent) and environmental (context) characteristics are primarily indirect, mediated through their impact on proximal processes (Bronfenbrenner, 1995). The evidence indicates that joint attention and parent-child book reading are important facilitators of children’s early vocabulary development.