This paper investigates the phenomenon of subject and object omissions in child Russian. Adult Russian differs from other languages (pro-drop languages such as Italian and non-pro-drop languages such as English) in apparent optionality in overt realization of arguments, which must be, nevertheless, contextually bound. Thus, in Russian the subject and object can be empty if their referents are recoverable from the linguistic (and sometimes situational) context, i.e. represent old information. As Russian provides confusing evidence to the child (e.g. both overt and empty elements are allowed), acquisition of such a confusing system presents a challenge for a developing system.

On the basis of longitudinal data from six monolingual Russian-speaking children, we show that children's performance is driven by the same (non-syntactic, non-morphological) factors as exist in adult Russian. Moreover, we argue that Russian-speaking children possess, rather early, a subtle knowledge of both syntactic constraints (such as the correlation between finiteness of verbs and overtness of subjects on the one hand and no such correlation for objects on the other) and discourse constraints.