This article evaluates postelector al conflicts in Mexico’s Oaxaca state before and after the state government legally recognized usos y costumbres—local leader selection via traditional practices (rather than parties and secret ballots). Assessing usos y costumbres within the normative debate between multiculturalists and pluralists on incorporation of ethnic minorities, the article compares the level of postelectoral conflict in usos y costumbres and non-usos y costumbres municipalities. It argues that since such conflicts have increased in Oaxaca over the last decade while simultaneously diminishing dramatically in Mexico’s other 31 states, the cause is probably unique to Oaxaca. Conflict may be at least partially attributed to perverse implementation incentives created by the law’s provocation of conflicts requiring mediation (rather than judicial verdicts). While further research is needed to test normative claims that usos y costumbres increase governing institutions’ credibility and foster positive group identities, the article concludes that while the customary practices “experiment” has failed at least by one criterion, it may warrant reconsideration if customary elections can be viewed as a set of evolving, instrumental processes, rather than as fixed, static, and essentialist conditions.