Citizenship at birth is by descent from a San Marino parent; the only territorial rule is a foundling provision for children born on the territory to unknown or stateless parents.
Sources: San Marino Citizenship Law No. 114/2000 (Consiglio Grande e Generale)
Citizenship by origin arises where a person is born of two San Marino citizens, or of one San Marino parent with a declaration of intent within twelve months of majority, or where the other parent is unknown or stateless.
Sources: San Marino Citizenship Law No. 114/2000 (Consiglio Grande e Generale)
Ordinary naturalization requires about thirty continuous years of registered residence (halved to fifteen for spouses of citizens), a clean record, and an oath; it is granted only by the Great and General Council through a special law passed by a two-thirds majority.
Sources: San Marino Citizenship Law No. 114/2000 (Consiglio Grande e Generale)