In the Republic? Laws regarding citizenship and census in the provinces often didn't exist--Augustus passed a number of laws that extended census counts to the provinces. There was a roll of citizens kept in the forum, and boys went down to the forum to register themselves when they came of age. With each census (nominally at the end of every five-year lustrum, but censors weren't always elected at each lustrum--the entire 1st Century, B.C. has something like five censorial elections) the roll of citizens would be adjusted, and the censors could strike citizens from the roll, move them around to different tribes, or place a nota (a bad mark) next to their names for stuff like cowardice in battle or extreme debt, for which they might suffer a variety of punishments ranging from fines to outright loss of citizenship--the Leges Clodiae introduced the right of appeal regarding nota. The census did not normally extend to the provinces during the Republic. The OCD mentions that the towns of Italy held their own census simultaneously with the Roman census--but this is Caesar's census, and there's no mention of whether local registration in Italy was done before Caesar, though I find it hard to believe that by the time Sulla abolished the censorship citizens throughout Italy were still required to trek to Rome to be registered. The only provincial census I know of before Augustus organized census registration throughout the empire is Cicero's remarks on the local censors of Sicily, whose duties were to evaluate the property of each person in the province for tax purposes, somewhat different from the Italian censors. But this is also Sicily, which during the Republic was consistently taken advantage of economically and is therefore not necessarily an ordinary province. Surely some sort of records were kept, otherwise taxes and the various expenses provincials owed to their governor's army and administration wouldn't work right, although they must've been at the discretion of the promagistrate governor. Augustus organized census registration throughout the provinces