The study investigates whether the variation in religious festivals' features and timing affect long-run economic development in Mexico. Specifically, the study examines whether "agriculturally coinciding" festivals (those coinciding with peak planting or harvest months) influence the long-run economic development of localities. Findings indicate that overall, festivals that coincide with agricultural seasons negatively influence both household income and development outcomes. These negative consequences can be due to persistently lower agricultural productivity, which impedes the structural transformation of the economy from agriculture to modern sectors. However, these festivals may persist as they lead to higher religiosity and social capital. (7 figures, 4 tables, references) 1179/39