Although the sexual abuse of children is a long-standing problem that has received considerable scholarly attention, still little is understood about sex offenses that occur by means of, or are facilitated through, the Internet. Increasing awareness of the Internet as a platform for the perpetration of sexual crimes has raised new questions on this aspect of criminal behavior. Of interest, for example, is whether those who engage in Internet-related sex crimes are a distinct type of sexual offender, or whether these offenders "merely" use newer technological methods to facilitate or perpetrate offenses. Moreover, little is known about the patterns, motivations, or typological similarities among types of individuals who use the Internet to commit sexual crimes. Of further concern is the risk posed by this class of sexual offenders, particularly the extent or rate at which those with an Internet-based conviction will escalate to (or have already engaged in) other types of sexual offences, especially "hands on" or contact sexual offenses. In reviewing the current empirical literature and drawing attention to areas of research need, this chapter addresses these and other pertinent questions related to use of the Internet in the commission of sexual offenses This chapter also draws focus to the importance of international cooperation, including policing, industry, (e.g., Internet Service Providers [ISPs], finance companies), and non-governmental organizations (NGOs), in the control and persecution of these offenses. Given the still limited empirical knowledge in this area, coupled with the inherently global nature of the Internet and the pace of technological advancement, the prosecution of Internet-based sexual crimes poses unique challenges that require thoughtful and rigorous scholarly attention.