The electronic monitoring (EM) of offenders, mostly using radio frequency (RF) technology to enforce home confinement, has been practiced in Europe for a quarter century. At least twenty seven countries make use it, at a range of points in the penal process. More seem likely to adopt it in the future. Few countries use it on a very large scale, compared to prisons and other community sanctions. Nowhere has it had a transformative effect on penal practice, although some countries have used it more wisely than others. In Western Europe, Germany has been the most reluctant user of RF EM, while the Scandinavian countries, Denmark especially, have arguably made the most creative use of RF EM in the context of their conditional prison sentences, to augment existing support and rehabilitation services for offenders. Some Eastern European and Balkan countries have sometimes used EM without the constraining effects of “probation values”. Pan–European attempts by the CEP (The European Probation Organisation) and the Council of Europe to shape and constrain the development of EM, given the perception that it could easily become a repressive technology, have been of some value. GPS tracking of high risk offenders now exists on a very small scale in a number of European countries, but government aspirations in England and Wales, which may or may not come to fruition, to develop a large scale GPS-based programme in the near future may signal the beginnings of an attempt to  the use EM in more penally transformative ways, although it is probation rather than prison use  which may be diminished as a result. The conclusion suggests that EM should be understood as a form of e-governance, that it should be theorized in terms of the “network society” and that its expansion is an expression of neoliberal penality.