Lexical development in first language (L1) Turkish and second language (L2) German in two- to three-year-old children was explored, using parental vocabulary checklists in Turkish and in German. Children displayed strong Turkish dominance in the number of lexical items they generated, which was due to the more frequent exposure to Turkish and higher quality of the input. Their vocabulary in Turkish and German covered a mostly different conceptual make-up, as evidenced by a high conceptual count of items across languages. Translation equivalents made up around 10% of the Total Vocabulary. An exemplary analysis of six noun categories displayed that the more domestically oriented categories (Furniture, People) were represented more strongly in Turkish vocabularies, while the Food and Drink category contributed equally to both languages. In Turkish, 18% of words were verbs, whereas in German, verbs constituted only 7% of the children’s vocabularies. A comparison between the parent checklists TIGE (developed for Turkish monolingual children in Turkey) and TILDA (developed for Turkish children growing up in Germany) disclosed conceptual differences, which can be attributed to culture-specific developments and use of specific lexical items in the two countries. Therefore, language- and culture-specific instruments should be employed to evaluate early vocabulary skills.