The number of bilingual children is growing dramatically all over the world. In 2010 the International Organization of Migration documented 214 million migrants worldwide, many bilingual (Koser & Laczko, 2010). One of the challenges arising from the rapid increase of bilingual children is scientifically grounded assessment of linguistic proficiency in both of a child's languages in various language domains. Assessment in both languages is especially important to avoid misdiagnosis of language impairment. Specific language impairment (SLI) is among the most prevalent impairments, estimated to affect 7%–10% of children entering formal education (Grimm, 2003; Tomblin, Smith, & Zhang, 1997). Assessment tools for bilinguals in both the home language and the majority language are often lacking (for exceptions, see Gagarina, Klassert, & Topaj, 2010; Schulz & Tracy, 2011).