A pilot study was conducted to determine if a nutritional intervention aimed at portion control leads to significant weight loss in a community of low-income Mexican American women. Nineteen low-income Mexican American women were randomized to a standard care group or an intervention group in portion control. The trial was 20 weeks in length, and the intervention included four 2-hour classes. Both interventions were administered by a certified nurse-midwife (CNM) and a promotora de salud (i.e., lay health advisor). Women in the intervention group lost more weight than women in the standard care group, though this difference was not statistically significant. The mean weight loss in the intervention group was 6.57 pounds (2.9 kg) compared to a mean weight loss of 2.8 pounds (1.3 kg) in the standard care group (P = .47). Mean weight loss, regardless of group, was significantly greater when participants reported self-weighing (P = .02). This pilot study in portion control for low-income Mexican American women merits further study.