Nutrition transition theory describes a progressive substitution of local staples for industrialized processed foods in local diets, a process documented diversely across world regions, and increasingly observed in rural areas of the global south. Here we examine the role of conditional cash transfer programs, in particular the emblematic Brazilian Bolsa Família (BFP), in driving nutritional transition in rural areas of the Amazon. Based on ethnographic research with both participating and nonparticipating women in the Amanã Sustainable Development Reserve (SDR), our analysis integrates Food Frequency Questionnaires (FFQ), seasonal 24-hour food intake recalls, and stable isotope ratios in fingernails to examine dietary behavioral change. Contrary to dietary changes observed elsewhere in the Amazon, participation in the BFP is not associated with a significant substitution of local staples for industrialized processed foods in Amanã. While an increase in the consumption of some industrialized foods was observed, it has been selective and it has not changed the structure of diets. Factors such as social and cultural value of local staples, resident's involvement with the SDR, their relationship with lake and upland forest and agricultural environments, and limited market access have buffered the expansion of industrialized processed foods as observed elsewhere.