Initial studies of legislative behavior in post-communist Ukraine suggest that party affiliation plays a significant role in legislator voting decisions. Yet, the intense debate in the US Congress literature on party effects suggests that finding effects can be problematic. The article contends that there was evidence of party effects in the mixed-member Verkhovna Rada (1998e 2002). An analysis of party switching demonstrates that those parliamentary parties linked to powerful political and economic elites were able to affect substantively the preferences of party switchers. While this analysis establishes the existence of party effects, the ability of a party to affect deputies does not depend on the strength of the party label as it does in the US case.