Unlike citizenship of other states, which is based either on jus sanguinis (birth from a citizen, even outside the state's territory) or on jus soli (birth within the territory of the state), citizenship of Vatican City is granted jus officii, namely on the grounds of appointment to work in a certain capacity in the service of the Holy See. It usually ceases upon cessation of the appointment. Citizenship is extended also to the spouse, parents and descendants of a citizen, provided they are living with the person who is a citizen.
Anyone who on loss of Vatican citizenship possesses no other citizenship, as judged by Italian law, automatically becomes an Italian citizen.
As of 31 December 2005, there were, apart from the Pope himself, 557 people with Vatican citizenship, while there were 246 residents in the state who did not have its citizenship.
Of the 557 citizens, 74% were clergy:
58 cardinals, resident in Rome, mostly outside the Vatican;
293 clergy, members of the Holy See's diplomatic missions, resident in other countries, and forming well over half the total of the citizens;
62 other clergy, working but not necessarily living in the Vatican.
The 101 members of the Papal Swiss Guard constituted 18% of the total, and there were only 43 other lay persons with Vatican citizenship.