In this paper, I examine the impact of party-switching on legislator's roll-call votes in Brazil. About one-third of deputies change party during each four year term; some change as many as seven times. Such volatility challenges basic concepts of representation -- if legislators change their policy positions to accomodate their new party, they violate the basic utility of party labels for electoral information cost reduction. This research has an additional utility. Legislative scholars agree that political parties are important parts of modern democracy, but roll-call based measures of party influence cannot separate out the influence of legislators own preferences and party directives. Analyzing the behavior of switchers before and after they change party gives us leverage on this and the ongoing "do parties matter" debates. I find significant and consistent party effects on legislative behavior, even when controlling for executive influence.