Dr. Taylor has had two major lines of research. One line involved the study of biological, psychological, cognitive, and environmental factors related to substance use disorders, personality disorders, and their comorbidity. The other line of research involved the study of genetic and environmental influences on externalizing problems, personality, and academic achievement. The Florida State Twin Registry includes over 2,600 twin pairs in Florida with data on reading achievement, personality, home environment, and internalizing and externalizing problems.