Objectives. We investigated preventive health behaviors (bicycle helmet, seat belt, and sunscreen use), physical activity, television viewing or video game playing, and nutrition (fruit, vegetable, milk, and soda consumption) among Asian and Latino adolescents living in the United States; assessed trends across generations (first-, second-, and third-generation immigrants or later); and compared each generation with White adolescents. Methods. We used data from 5801 adolescents aged 12 to 17 years in the representative 2001 California Health Interview Survey. Results. In multivariate analysis, first-generation Asians measured worse than Whites for preventive health behaviors (lower participation), physical activity (less activity), and television viewing or video game playing (more hours), but improved across generations. For these same behaviors, Latinos were similar to or worse than Whites, and generally showed no improvement across generations. First-generation Asians and Latinos had healthier diets than Whites (higher fruit and vegetable consumption, lower soda consumption). With succeeding generations, Asians' fruit, vegetable, and soda consumption remained stable, but Latinos' fruit and vegetable consumption decreased and their soda consumption increased, so that by the third generation Latinos' nutrition was poorer than Whites'. Conclusions. For the health behaviors we examined, Asian adolescents' health behaviors either improved with each generation or remained better than that of Whites. Latino adolescents demonstrated generally worse preventive health behaviors than did Whites and, in the case of nutrition, a worsening across generations. Targeted interventions may be needed to address behavioral disparities.