This paper addresses one of the central problems in mental grammar studies - the problem of modularity in anaphoric processing. Our study is based on Reuland's model "Primitives of binding" arguing that anaphoric relations can be established in three independent language modules: syntax, semantics, and discourse. These modules work sequentially: from the most economic syntax to the least economic discourse. We conducted a series of experiments with healthy adult native speakers of Russian (control group), 4-5 year old children with no speech problems, and participants with agrammatic aphasia. Pronoun interpretation in sentences where syntactic and semantic analyses lead to different interpretations was studied. We found that children and adults with aphasia rely on semantic analysis in cases where the control group relies only on syntax.