Adopting a bimodal bilingual language acquisition model, this qualitative case study is the first in Germany to investigate the spoken and sign language development of hearing children of deaf adults (codas). The spoken language competence of six codas within the age range of 3;10 to 6;4 is assessed by a series of standardised tests (SETK 3-5, TROG-D, PDSS). Additionally, a language assessment tool designed specifically for hearing bilingual children named HAVAS 5 is employed to measure both the children's spoken and sign language abilities. A heterogeneous picture emerges: all codas show abilities equal to those of monomodal monolingual children in their age range with regard to German sentence structure and verb inflection and an extensive receptive vocabulary, but deviations from the age norm are observed for the production of verbs and prepositions. Furthermore, three codas show below average T-values in some grammatical subtests. Overall, the findings suggest that at least some codas may acquire both of their languages (i.e. spoken and signed German) simultaneously. However, our study also indicates that the spoken language development of some codas as well as the acquisition context of this minority group strongly resembles a form of successive language acquisition that is known from children who acquire German as an early second language in a migration background.