This study investigates the adult grammars of French simultaneous bilingual speakers (2L1s) whose other language is German. Apart from providing an example of French as heritage language in Europe, the goals of this paper are (i) to compare the acquisition of French in a minority and majority language context, (ii) to identify the relative vulnerability of individual domains, and (iii) to investigate whether 2L1s are vulnerable to language attrition when moving to their heritage country during adulthood. We include two groups of German-French 2L1s: One group grew up predominantly in France, but moved to Germany during adulthood; the other group grew up predominantly in Germany and stayed there. Performance is compared in different domains, including adjective placement, gender marking, articles, prepositions, foreign accent and voice onset time. Results indicate that differences between the two groups are minimal in morpho-syntax, but more prominent in pronunciation.