The MEC is a population-based, multi-ethnic cohort of over 215,000 adults aged between 45 and 75 years, resident in Hawaii and Los Angeles in the United States of America. Recruitment began in spring 1993 and was completed in 1996, with eligible individuals identified from several sources, including voters' registration files and drivers' license files. Participants were recruited across 5 main ethnic groups: African American, Caucasian, Japanese American, Latino, and Native Hawaiian. The cohort also included a small number of Filipinos, Samoans, Koreans, and other ethnic groups. Of the baseline cohort, around 49% resided in Hawaii, and around 51% resided in California. Follow-up is conducted both passively through data linkage and actively through follow-up questionnaires.