A United States Permanent Resident Card, also Green Card, is an identification card for a lawful permanent resident (LPR) of the United States of America. Green Card also refers to a process of becoming a LPR. Green Card serves as a proof that its holder has permission to conditionally reside and take employment in the U.S. The holder must maintain resident status by residing in the United States and can be removed (if certain crimes are committed, for example).

Official name of the card is Permanent Resident Card (form I-551). The name "green card" comes from the fact that the predecessor, form I-151 Alien Registration Receipt Card, introduced at the end of World War II, was printed on green paper. Form I-551 was adopted in 1977 and has been printed on paper of various colors, none of which were green, but the term "green card" has nonetheless remained in use. As of 2006, the card is mostly yellowish-white and the only prominent green feature is the background of the lettering on the back. A card includes the holder's name and photograph, and other information, and has been updated over the years with numerous anti-counterfeiting devices.

Green cards were formerly issued by the Immigration and Naturalization Service (INS). That agency has been absorbed into and replaced by the Bureau of Citizenship and Immigration Services (BCIS), part of the Department of Homeland Security (DHS). Shortly after re-organization BCIS was re-named to U.S. Citizenship and Immigration Services (USCIS).

If an immigrant wants to work while his application for a green card is pending, a temporary work permit, Employment Authorization Document (EAD), is needed. If an immigrant wants to travel abroad while his application for a green card is pending, alien has to obtain advance parole travel document.