The ability of all people to move more easily across international borders has brought with it the specter of the mobile offender, including the person who might commit sexual offences. This article explores why the sex offender, in particular, might want to travel to commit further offences, and what devices can be employed to minimize the possibilities of such movement and prevent further offending. Taking the United Kingdom as a case study, the article looks at ways of identifying the incoming sex offender and ensuring that the outgoing offender only leaves after notifying the police of his intentions. The ways of preventing a sex offender from traveling from the United Kingdom are also considered. (Published Abstract)