The study was conducted by researchers at the University of Twente in cooperation with a team of police and criminal analysts from a special international criminal investigation department that focuses on organized crime from eastern Europe and Turkey. Data and information were obtained from police sources and interviews with persons involved in the prostitution business. Special attention is given to the modus operandi and to the nature of the criminal groups involved. The findings show that during the last few decades, the prostitution sector in the Netherlands has expanded rapidly and has become more international. There has recently been an increase in the number of prostitutes from eastern and central Europe who are active in Holland in brothels, clubs, and behind windows in "red light" districts in the cities. Although the majority of the women travel to the Netherlands voluntarily, they are victimized by cliques of loosely organized professionals as well as by organized crime groups of various nationalities. All arrested offenders have been career criminals. Most of the criminal groups are also involved in smuggling drugs, arms, and stolen cars. In the field of trafficking women, there is collaboration between eastern and central European criminals and their Dutch, Turkish, and former Yugoslav counterparts. Initial recruitment in the homelands is done by the local criminals. Because prostitution is viewed as a more or less legal economic activity, the Dutch police, until recently, neglected the social problem of victimization of prostitutes. Moreover, criminals active in trafficking and exploiting women from eastern and central Europe do not fear detection and prosecution and will not be deterred by relatively low sentences. 1 table and 19 notes