In this issue (see page 380), Buu and colleagues expended the spectrum of causes of health disparities by comparing differences in mortality rates and risk factors for worse lung disease between Hispanic and non-Hispanic patients with CF in California. The Hispanic population is the second largest ethnic group in the United States, characterized by younger age, less education, and less wealth, and with a very large immigrant component. It has been already shown that the population of Hispanic people with CF from the entire United States has an increased prevalence of important risk factors for morbidity and mortality. Here, Buu and colleagues retrospectively analyzed the Cystic Fibrosis Foundation Patient Registry data of California residents who were diagnosed in or after 1991 and who were aged <18 years. They found that patients of Hispanic ethnic origin who had CF had a mortality rate 2.8 times higher than that of non-Hispanic patients. Furthermore, lung function measured by FEV1 was significantly lower for Hispanic patients than for non-Hispanic ones at age 6 years. However, the more severe disease among Hispanic patients with CF was independent of biological, diagnostic, clinical, and social factors that were previously shown to be associated with increased mortality. Furthermore, no difference was observed in access and use of CF center care, age at diagnosis, and nutritional status. The question thus remains, what causes the poorer outcome for Hispanic patients with CF? One reason could be modifier gene(s); however, this is unlikely since Hispanic people are not a homogeneous closed population. Hence, poverty and social class contributed to differences in health outcomes but could not be fully accounted for in the data. Since there was no difference in accessibility to CF centers and medicine, there must be additional contributing factors associated with ethnicity, such as adherence to treatment regimens, self-management, culture, health literacy, and English proficiency,, that contribute to acceleration of the disease process.