Sorry, but no. An immigrant who marries a U.S. citizen must apply for a green card (U.S. permanent residence). This is a long process involving many forms and documents. The immigrant can be refused entry if he or she is found inadmissible, perhaps because of a medical problem, criminal history, past immigration violations, or the U.S. immigration authorities' belief that the marriage is a fraud to get a green card. After successfully obtaining a green card, the immigrant spouse can, after three years as a permanent resident, apply for U.S. citizenship. (This assumes that you're still married and living together when the immigrant applies. If not, the waiting period changes to five years.)