Background: In January 2014, Mexico implemented a tax on sugar-sweetened beverage (SSB) purchases of 1 peso/L. Objective: We examined the heterogeneity of changes in nonalcoholic beverage (SSB and bottled water) purchases after the tax was implemented by household income, urban and rural strata, and household composition. Methods: We used 4 rounds of the National Income and Expenditure Surveys: 2008, 2010, 2012, and 2014. Changes in purchases in per capita liters per week were estimated with the use of 2-part models to adjust for nonpurchases. We compared absolute and relative differences between adjusted changes in observed purchases in 2014 with expected purchases in 2014 based on prior trends (2008–2012). The models were adjusted for sociodemographic characteristics of the households, place of residence, and lagged gross domestic product per capita. Results: We found a 6.3% reduction in the observed purchases of SSBs in 2014 compared with the expected purchases in that same year based on trends from 2008 to 2012. These reductions were higher among lower-income households, residents living in urban areas, and households with children. We also found a 16.2% increase in water purchases that was higher in low- and middle-income households, in urban areas, and among households with adults only. Conclusions: SSB purchases decreased and water purchases increased after an SSB tax was imposed in Mexico. The magnitude of these changes was greater in lower-income and urban households.