The history of religion in Italy reveals both a continuing Catholic presence and growing religious diversity. This chapter traces this history from medieval times, through early modern, pre-unification Italy, to the struggle for unity, the forcible end of the Pontifical States, and the problematic coexistence of the Holy See, the Catholic Church, and the Kingdom of Italy after 1861. The later sections deal with the appeasement of the Holy See under fascist rule and the Lateran Pacts of 1929; then the transition from fascism to democracy and from monarchy to republic, through the referendum of 1946 and the Constitution of 1948. Central to this evolution is the explicit acknowledgment that Italy is no longer a Catholic state; conversely laicità is identified as the supreme constitutional principle. Since 1989, cultural Christianity and the consolidation of various forms of Catholic preference are learning to coexist with an increasingly multi-religious population.