Today, irregular migration is treated as a criminal offence in most European countries. No longer regarded merely as an administrative issue, unauthorised entry (and stay) is sanctioned by fines, imprisonment and expulsion. Yet, what impact does this approach—the so-called “criminalisation of migration”—have on migrants and receiving societies? Does it deliver the security it promises? And how does it shape security perceptions and dynamics? This chapter examines the cases of Italy and France, two of the countries with the most severe sanctions in Europe, and argues that criminalisation creates a feedback loopCriminalisation feedback loop, exacerbating insecurity and irregularity.