The article focuses on whether and to which extent heritage bilinguals make use of their heritage language while developing receptive skills in unknown languages which are either related to the majority language or the heritage language. Thirty four adolescent heritage speakers of Russian and Polish and a control group of thirty three German monolinguals were first exposed to a text in Swedish. The monolingual control group was matched with regard to age, educational background, foreign languages learned at school as well as proficiency in English. All participants had to determine the parts of speech of ten items from the text, translate them into German, and extract the main pieces of information from the text. In a second step, the heritage speakers completed a similar task with an unknown Slavic target language (Serbian). The results revealed no bilingual advantage of the heritage speakers over the monolinguals in the Swedish task. Furthermore, they scored lower in the Serbian trial. We treat this as evidence that access to the heritage language as a resource for solving these tasks is limited compared to the majority language and English which might be due to lesser metalinguistic knowledge about structures of the heritage language.