This study discusses the supportive role of the institution, in relation to family language policies, in the context of heritage language use in Germany and Spain. Furthermore, it studies the (positive) influence Spanish (as a heritage language) might have on German in the context of Spanish-German bilingualism. 66 Spanish-German bilinguals (mean age: 4;6) are analyzed cross-sectionally and compared with 11 longitudinally studied children of each language. We observe that German language proficiency (measured with MLU) grows progressively with age, while Spanish acquired in Germany exhibits high values similar to those of Spanish as an environmental language in the first age group analyzed (2;4-3;3), although from 3;4 onwards it stagnates at an MLU of 2.5. This result cannot be explained by family language policies alone (presence vs. absence of OPOL). More specifically, it will be argued that the institution in Spain has developed more supportive strategies for heritage language use than the one in Germany. The analysis of the children’s use of Root Infinitives in German shows, however, that a (low) MLU of 2.5 in the heritage language (Spanish with a highly inflecting verb system) is enough to help get rid of a non-target-like structure faster than in monolingual German children.
