From 1 January 2014, Mexico implemented an excise tax of 1 peso per liter on sugar sweetened beverages and an 8% tax on nonessential food products (junk food tax). In both cases, longitudinal models that examined how pretax trends in SSB and food purchases of a representative sample of Mexican urban consumers were studied. A panel of households who kept all receipts and all containers along with registering the location of the purchases were surveyed biweekly to create the longitudinal data used for these analyses. Outcomes were volumes of beverages and grams of foods. The results for both studies on impact of the tax overall and on different socioeconomic (SES) groups were comparable. Consumption declined significantly of the taxed items with the largest impacts in low and middle SES consumers. Purchases of taxed beverages decreased by an average of 6% in 2014 compared with expected purchases without the tax. Furthermore, these reductions became large over time, reaching a 12% decline by December 2014. All three socioeconomic groups reduced purchases of taxed beverages, but the reduction was greatest among households of low socioeconomic status, averaging a 9% decline during 2014 and reaching a 17% decrease by December 2014 compared with pretax trends. For taxed foods, there was a 5.1% decline change beyond what would have been expected based on pre-tax (2012-2013) trends, with no corresponding change in purchases of untaxed foods. Low SES households showed greater response to the tax, purchasing on average 10.2% less taxed foods than expected, whereas middle and high SES households purchased 5.8% and 2.3% less taxed foods than expected, respectively. Additional research examined trajectories of consumption for high and low consumers prior to the tax and after them. High consumers significantly reduced both SSB’s and taxed food much more than others.