For Daller (2011) there are several aspects involved in assessing language when specifically targeting multilingual speakers. Research should thus reflect on which language skills to test in terms of the differentiation between competence vs. performance, but also choose methods that address the research questions at hand. It is necessary to reflect on how assessment is conducted – through self-ratings or/and productive data – on what is being tested - productive and/or receptive skills; written and/or oral language – and which type of instruments are going to be applied - tests, observation tools and/or profile analyses (elicitation form). For bi- or multilinguals two main issues are also of focal relevance: the norm chosen in the assessment and the capturing of cross-linguistic transfer (Treffers-Daller & Sakel 2012). The paper uses the framework proposed by Daller (2011) and Treffers-Daller & Sakel (2012) towards testing multilinguals to analyse and compare language testing methods of six projects funded by the German Ministry for Education and Research and addressing the issue of multilingualism and language formation within school settings. The focus will be on capturing the family languages of multilingual speakers and making cross-linguistic inferences.