This case study investigates the acquisition of Russian in a language contactsituation. It examines a simultaneous Swedish-Russian bilingual child born andraised in Sweden. Qualitative analysis is provided from age 1;4 to 8;5 focusingespecially on the earliest stages (before the end of the critical period at4;5). The aim was to investigate (a) whether the child reaches the samemilestones as monolingual children, (b) whether there is evidence that twoseparate linguistic systems have been developed, (c) whether the child'sgrammatical competence in both languages might be qualitatively different fromthat of monolingual children and (d) whether there is interaction between thelanguages. The hypothesis tested is that ample input is needed to construct anddevelop two linguistic systems on a native-speaker level.