The problem addressed in this phenomenological study is how culture and acculturation can potentially influence gestational weight during pregnancy, leading to overweight and obesity among immigrant Latinas. To understand the possible influence of culture and acculturation on the diet, exercise, and weight of pregnant immigrant Latinas, the experiences of immigrant Latinas who had undergone a pregnancy in Mexico and were pregnant in California were examined. The ecological model theory was applied as a framework for exploring the participants' experiences regarding nutrition, physical activity, and weight gain. Semistructured interviews with 10 qualified participants were conducted. Data analysis entailed an inductive approach based on the following phases of qualitative data analysis: data reduction, data display, and conclusion and verification. Clustered responses were presented around the major themes. Six major themes were derived from the data. These were: (a) bicultural lifestyles; (b) personal adjustments relating to pregnancy and prenatal care; (c) low levels of social and relational support; (d) adjustments regarding diet, nutrition, food security, and access; (e) changes in the form and extent of physical activity in the United States; and (f) rapid weight gain experienced during pregnancies undergone in the United States. Social change implications include encouraging public health professionals, health educators, and community health workers to focus on the importance of culture and acculturation on the health of Latinas in order to ensure positive infant and maternal health outcomes.