This paper analyses the effects of direct and indirect early parental investments on the German-language development of 3–5-year-old children of Turkish immigrants and native German children. Since Turkish parents are on average less proficient in German than native parents, it is hypothesised that Turkish children cannot profit as much as German children from activities inside the family (e.g., frequency of parental reading to child). For the same reason, activities outside the family (e.g., attendance at playgroups) might then be of special importance for their acquisition of German-language skills. Used for the empirical analyses are the data of the project ‘Preschool Education and Educational Careers among Migrant Children’, which includes a repeated measure of children’s German vocabulary over a one-year period. It is demonstrated that German children can profit more than Turkish children from activities inside the family, while the opposite is true regarding activities outside the family. Additional analyses with the Turkish sample show that a higher frequency of activities inside the family improves Turkish children’s German vocabulary only under the condition that their parents have a good command of German. The findings indicate that activities outside the family are a very effective means of fostering development of the second language among migrant children.