The Hispanic population in the United States is diverse in many respects. Although there is marked variation in the prevalence, morbidity, and mortality of asthma among Hispanic subgroups in the United States, these differences are poorly understood. Future studies of asthma should include large samples of Hispanic subgroups that are well characterized in terms of self-reported ethnicity, country of origin, place of birth, area of residence, and indicators of socioeconomic status. Because a significant proportion of Hispanics live in poverty, public health interventions aimed at improving access to health care and housing conditions would have a major impact on reducing asthma morbidity among Hispanics in the United States.