I have dual Italian/American Citizenship. I believe that after three years of marriage, I can pass Italian citizenship to my Thai spouse - Will the Thai government allow her to hold both citizenships or must she renounce Thai citizenship? Will the Italian government allow her to have Thai/Italian citizenship?

Will our children be able to have all three American/Italian/Thai?

I have dual Italian/American Citizenship. I believe that after three years of marriage, I can pass Italian citizenship to my Thai spouse - Will the Thai government allow her to hold both citizenships or must she renounce Thai citizenship? Will the Italian government allow her to have Thai/Italian citizenship?

Will our children be able to have all three American/Italian/Thai?

If you are living outside Italy your wife can apply for italian citicenship after 3 years of marriage date.Time required for approvation one to two years.

She doesn't need to renounce the Thai citicenship.

The Italian government will allow her to have both.

Don't know the American law provisions.

to be more precise, if you marry and reside in Italy one can apply for citizenship after 6 months, OTH if living abroad you must wait 3 years before applying. Final decision may vary depending on your case, usually is 6 to 12 months. May take longer if case is difficult. To echo abduirahman, Italian law permits dual nationality, so she won't have to renounce Thai citizenship. Same applies to Thai laws. Don't have a clue about American laws and practices. I never heard anyone holding 3 nationalities / passports but hey maybe somebody here may prove it possible.