Who can sponsor relatives for U.S. immigrant visas for permanent entry?

A U.S. citizen may sponsor a spouse, parent, sibling, minor child or adult child (regardless of marital status), or fiancé for an immigrant visa (more commonly called a green card). However, a lawful permanent resident (green card holder) may only sponsor a spouse, minor child or unmarried adult child. Both citizens and permanent residents must agree to financially support their sponsored family members and meet a certain level of earnings.