This case study investigates the acquisition of Russian in a language contact situation. It examines a simultaneous Swedish-Russian bilingual child born and raised in Sweden. Qualitative analysis is provided from age 1;4 to 8;5 focusing especially on the earliest stages (before the end of the critical period at 4;5). The aim was to investigate (a) whether the child reaches the same milestones as monolingual children, (b) whether there is evidence that two separate linguistic systems have been developed, (c) whether the child's grammatical competence in both languages might be qualitatively different from that of monolingual children and (d) whether there is interaction between the languages. The hypothesis tested is that ample input is needed to construct and develop two linguistic systems on a native-speaker level.