The aim of this article is to address the two strictest forms of immigration control in Italy: penal and administrative detention. The first core section of the article discusses key trends in the use of penal detention against foreigners and immigrants, whilst the second and longest core section of the article explores key trends in the administrative detention of irregular migrants. As concerns penal detention, it is shown that the significant growth of Italy’s prison population over time has been because of a rapid rise in the number of foreign prisoners, which has outpaced the decline observed in the number of their Italian counterparts. As regards administrative detention, which was first introduced in Italy in 1998 for irregular migrants who cannot immediately be deported, the article demonstrates that only a proportion of irregular migrants transit through a CIE (Centro di Identificazione e di Espulsione, or Identification and Deportation Centre). This is because of the high selectivity that is exhibited by Italy’s administrative detention system, itself based on a range of considerations, from the availability of beds and the likelihood of repatriation for apprehended migrants to public opinion. The findings of this article also imply that there has been an impressive degree of consistency in the immigration control policies adopted by governments of different party-political orientation.