A temporary I-551 stamp is issued in a foreign national passport to indicate that the person is a permanent resident of the United States. The stamp is official notification of the person's residency until they receive their I-1551 card, commonly known as the Green Card. Getting the stamp requires a lengthy documentation. There are also several different ways to go about receiving this stamp.
Make sure that you qualify to apply to become a permanent resident in the United States. A person can be sponsored for residency by their U.S. employer, by family in the country, through marriage to a citizen or through other special circumstances that are outlined through the U.S. Department of State. Those that qualify can continue with the permanent resident application process.
Complete the I-485 Application to Register for Permanent Residence or Adjust Status. The form can be downloaded from the U.S. Citizenship and Immigration Services (USCIS) website as a PDF file. The permanent resident application asks several questions regarding citizenship information, passport information, how long you have been in the United States, information regarding your family and dependents, and military information.
Compile all other documentation that will be requested from the USCIS. This will include a valid national passport, a money order for the application fees (as of 2010 the application fee was $1,010), any documentation that the USCIS may request about your sponsor (family information, marriage certificate, employment contact, etc). You will also need two additional passport photos. This documentation will have to be submitted the same time as the I-485 Application to Register for Permanent Residence or Adjust Status.
Submit the application and all supplemental documentation to the USCIS. The USCIS will take the application and all requested documentation (along with your national passport) and process the application.
Receive your passport from the USCIS. If the permanent resident application is approved, you will receive the I-551 stamp in the passport. The stamp is a temporary and normally valid for one year after the issue date. After you receive the I-551 stamp you should receive your I-551 card (Green Card) within a couple of months.