Data has been taken from the Hungarian National Assembly, where the mandate type (single member district (SMD) vs. party list or proportional representation (PR)) changes for a number of legislators each term, to explore whether and how such changes lead to changes in legislators' voting behavior. When the electoral system under which a legislator was elected changes from PR to SMD, then the rate at which the legislator defects against the party line of voting increases significantly. Contrary to expectations, when the electoral system changes from SMD to PR, there is no significant change in the voting behavior of legislators. Additional robustness tests confirm these results. The lasting influence of reputations and habits may account for the asymmetric results. * Washington University in St. Louis (emails: olivella@wustl.edu, tavits@wustl.edu). We would like to thank Thames 2005. Another possibility is to compare different legislative chambers in the same country if these chambers employ different electoral rules (see, for example, Desposato 2006). However, these situations are rare, and, therefore, MMS has become a more commonly used setting for studying the causal connection at hand.