A study of alcohol and drug use among migrant and seasonal farmworkers in Orange and Lake counties (Central Florida) was conducted in 1978 to determine substance abuse among migrant and seasonal farmworkers, the subgroups with substance abuse problems, the farmworkers' knowledge of and attitudes toward alcohol and drug treatment programs, and the extent of their mental health needs. A questionnaire, administered in Spanish or English, was used to interview 875 respondents: 825 in a general sample and 50 in a network sample of known drug users. The farmworker survey indicated substance use patterns similar to those found in the "1977 National Survey on Drug Abuse". Results showed that drug use was strongly related to age and much of it was largely experimental; use of marihuana and illicit use of sedatives, barbiturates, amphetamines, and opiates increased with increased education; marihuana and alcohol use and nonmedical use of prescription drugs was lower among Hispanics than Whites or Blacks; alcohol was more widely used than illegal drugs across all ages; young adults (18-25) showed highest current use rates for all substances. Comparisons were also made for the smaller network sample and the Health Opinion Survey data. Recommendations include further research so that long-range strategies for primary prevention and intervention can be made along with improved service delivery to the farmworker community. (RS)