The AIDS epidemic has turned male homosexuality into a societal issue that can no longer be marginalized or ignored. In most Western countries, with the exception of southern Europe, the majority of people with AIDS were and still are gay men (HIV/AIDS Surveillance in Europe, 1995). Primarily as a consequence of the fear that men who have sexual contacts with men as well as with women might form a bridge between the affected gay community and the heterosexual population, interest in bisexuality has grown as well (Weinberg, Williams and Pryor, 1994).
The AIDS epidemic has stimulated much research into homosexual behaviour, nationally and cross-nationally; money to do so became available in an unprecedented way. For the first time, gay men, as a separate category of people, also became a target of extensive primary prevention. In some European countries, such as the Netherlands and Switzerland, gay men were even integrated into the campaigns directed at the general population. In other countries, such as France, AIDS has reactivated or fostered the growth of the gay and lesbian movements (De Busscher, 1995).
The research about gay men carried out prior to AIDS, as well as that conducted in the context of AIDS, has relied predominantly on convenience samples (Bochow et al., 1994). These studies have answered several important questions about homosexual behaviour. Since it has been shown that convenience samples of gay men tend to be biased (Weinberg, 1970; Harry, 1986 and 1990; Sandfort, 1996), these studies have also generated several other
*The author would like to thank Henny Bos, Stuart Michaels, Ernest de Vroome, Jeffrey Weiss and the group of researchers collaborating in the EU Concerted Action for their support in preparing and writing this chapter.