How does vocabulary in the heritage language develop? Does the social environment of the community have an influence? This talk presents empirical results regarding the development of expressive and receptive vocabulary in the heritage language and analyzes the effects of amount of exposure, use, socio-economic status, dominance, and community on the acquisition of vocabulary in the heritage language. A Russian-German and a Turkish-German speaking sample are compared: 211 children at the age of 6–10 years were tested with a standardized picture naming task in a cross-sectional design. The results show a good receptive mastery and a limited expressive command of vocabulary with large individual differences, and only a slight development in the timespan of four years. Between the communities we find systematic variation, which we attribute to social and pragmatic differences with moderator and mediator effects. Possible limitations of the results are discussed with respect to cross-linguistic test effects.