Mixed member legislative systems have proliferated in the last twenty years, and while our knowledge of the institutional impacts has grown, we have had difficulty in separating institutional and contextual (namely party) influences. Through an analysis of Taiwan before and after the implementation of a mixed member majoritarian (MMM) system, the level of contamination between tiers and variance between parties becomes clearer. Survey results show a marked shift in constituency focus for district candidates, moving from multimember to single-member districts, while (...) party list seats focus on district factors at higher rates post-reform. Variance between the two major parties further suggests differing levels of party pressure. (shrink)