We report on the results of a field experiment in Puebla, Mexico that informed randomly-selected households facing a nonlinear price schedule about how different electricity-consuming actions might change their electricity bills. Households that received this 20-minute, in-person intervention reduced their electricity use, with much of this reduction driven by those that paid the highest marginal price for electricity. The estimated impacts were durable with no observed rebound for at least a year. Households with less educational attainment reduced use the most, consistent with the conclusion that the intervention imparted new knowledge to consumers that led to this observed behavior change. The high rate at which customers accepted the intervention, the resulting consumption decrease, and low implementation costs make this intervention cost-effective relative to several previous energy conservation campaigns in Mexico.