Family unification is a major objective of the United States immigration laws. Because of this, several carefully defined groups are eligible to immigrate to the United States based on close family relationships. Immigrant visas are always available, in unlimited numbers, for immediate relatives of U-S citizens. An immediate relative is defined as a spouse, an unmarried child under 20 years of age, and the parents of a U-S citizen. Unlike immediate relatives of U.S. citizens, other family-based categories are allocated a limited number of visas. Because of the limitation, it may take several years before a visa is available for a foreign relative. According to the Immigration Marriage Fraud Amendments, aliens who obtain permanent residence by marriage are given such residence on a conditional basis. Two years after the individual receives this status, he or she must apply with the Immigration and Naturalization Services to have the conditional basis removed. If the individual doesn't apply to have this removed, he or she risks losing his or her green card. A new provision of the 1990 Immigration Act also allows foreign national widows of U.S. citizens to apply for permanent residence if they file an Immediate Relative Petition or form I-130. The Petition must be filed within two years of the citizen's death, and the spouse cannot be remarried. For more information on family-based immigrant visas, contact an attorney qualified in immigration law.