Under which circumstances do political jurisdictions engage in territorial reforms? Existing research on international, regional, and local integration and secession reforms has highlighted the pivotal relevance of jurisdictions' size and wealth. However, we lack quantitative and comparative evidence on the relative importance of these two factors as well as on their interaction. This paper analyzes referendum decisions on territorial reforms in Switzerland to answer this question. Using data from municipal merger referenda in 1477 municipalities that were involved in 418 merger projects since 2000, I examine how relative wealth and size are linked to the acceptance or rejection of a merger project. The results show that both having a lower tax rate than merger partners -- indicative of higher wealth -- and a small population share in the merger coalition -- indicating a lack of political control -- reduce voters' acceptance of merger projects in referendum decisions. Yet, a positive interaction effect between tax rate difference and relative size suggests that large municipalities are willing to trade wealth for political control by incorporating small and poor municipalities. The latter, by contrast, are willing to trade political control for wealth. These results have important implications for the design of politically feasible territorial reform coalitions.