The obesity epidemic in Latino children has reached staggering proportions. This study explored Latino parents' perceptions of their ability to prevent obesity in children. Three focus groups were conducted with 26 Latino parents of preschoolers at a New York City Head Start program. Parents perceived high levels of ability to prevent obesity primarily via dietary influence. Four factors negatively impacted parents' ability: family history, intergenerational and interparental issues, adolescence, and societal pressures. Culturally effective, family-based obesity interventions among Latinos should build upon parental perceptions of ability to prevent obesity, while simultaneously helping parents address the factors they perceive challenge this ability.