Abstract This study investigates the variation in null subject usage across Slavic languages, focusing on Polish, Russian, and Ukrainian. By examining the syntactic and interpretive conditions for null subjects in embedded subjunctive clauses, the paper highlights differences in subject–verb agreement, clause structure, and the role of complementizers. Polish, as a consistent null subject language, shows high acceptance of null subjects, while Russian and Ukrainian exhibit partial null subject behavior, with significant inter-speaker variability. A cartographic analysis reveals that clause size and syntactic movement play a crucial role in licensing null subjects, with Polish consistently realizing its complementizer in ForceP, and Russian and Ukrainian showing more variation. The findings highlight the importance of structural factors in explaining null subject distribution and contribute to a deeper understanding of this phenomenon in Slavic languages.
Frasson et al. (Tue,) studied this question.