Compared to their peers, Latina/o youth are at high risk of being overweight and obese and experiencing related health problems. Because of this, it is important to identify factors that may contribute to obesity among Latina/o youth. We explored the relationships among internal health locus of control (IHLOC), cultural factors (cultural orientation, ethnic identity), and Latina/o adolescents’ body mass index (BMI; an index of obesity and overweight). One hundred twenty-eight Latina/o adolescents (ages 13–18 years) completed a series of questionnaires to assess ethnic identity (i.e., affirmation-belonging and participation), cultural orientation (i.e., Latina/o cultural orientation and Anglo cultural orientation), and IHLOC. We also obtained participants’ reports of weight and height, which were used to calculate BMI. Results indicated that there was an inverse association between IHLOC and BMI; specifically, the greater internal control the adolescents perceived they had over their health, the lower their BMI. As expected, Latina/o cultural orientation moderated this relation, such that at moderate and high levels of Latina/o cultural orientation, IHLOC was associated with lower BMI. Contrary to expectations, ethnic identity affirmation-belonging moderated this relation in the opposite direction, such that at low and moderate levels of ethnic identity affirmation-belonging, IHLOC was associated with lower BMI. The importance of IHLOC, cultural factors, and context in obesity among Latina/o youth and the implications of these results for obesity intervention programming are discussed. (PsycINFO Database Record (c) 2018 APA, all rights reserved)