Theo Sandfort, trained as a social psychologist, was a tenured, Associate Professor at the Department of Clinical Psychology at Utrecht University, the Netherlands, and Director of the Research Program “Diversity, Lifestyles and Health” at the Netherlands Institute of Social Sexological Research (NISSO). Since 2001 he is Associate Professor and Research Scientist at the HIV Center for Clinical and Behavioral Studies.

Since his time as a graduate student Theo Sandfort has been involved in numerous basic and applied empirical investigations in the field of sexuality and health. He has worked as interviewer, research assistant, principal investigator and project leader. In terms of research methods he is skilled in both quantitative and qualitative approaches. He was involved in large as well as small-scale studies, aimed at surveying sexual behavior and attitudes, identifying determinants of health behavior, needs assessments, evaluating mass media and small-scale health interventions, and identifying the epidemiology of mental disorders.

While in the Netherlands, Dr. Sandfort acquired grants from national and local Dutch government, semi-governmental agencies, non-profit organizations as well as the industry. He has successfully received funding for over twenty-five studies, the largest of which have been Psychosocial Core of the Amsterdam Gay Cohort Studies (1992-1998), Monitoring the Effects of the Mass Media Safe Sex Campaigns (1992-2001), Sexual Harassment and Minorities in the Dutch Police Force (1998-2001).

Dr. Sandfort is on the Editorial Board of several academic journals, including AIDS Care, Archives of Sexual Behavior, Culture, Health and Sexuality, International Journal of Sexual Health, Journal of Gay and Lesbian Mental Health, Sexualities, Sexuality Research and Social Policy, and Tijdschrift voor Seksuologie (Dutch Journal of Sexology).

He served as President of the the International Academy of Sex Research and the Dutch Society of Sexology. In 2008, he received the John Money Award from the Society of the Scientific Study of Sexuality for his research work.

Jeffrey Weeks OBE (born 1945, in Rhondda, Wales) is a historian and sociologist specialising in work on sexuality, and is also a gay activist.