Mexico’s election management system enjoys wide international recognition, and yet seemed unable to stand the test of the razor-thin presidential election in 2006. Using the Mexico 2006 Panel Study, we find that neither credibility in the electoral institutions nor perceptions of the cleanness of elections were strong determinants of political protest. Rather, a combination of long-term trends and short-term effects brought about the demonstrations. From this perspective, Mexico’s postelection mass protest seems less fundamental than apparent, and also less spontaneous. To the extent that the basic issue of improved economic opportunity remains unsolved, it may still be potentially destabilizing in the future.