The unauthorized or undocumented resident immigrant population is defined as all foreign-born non-citizens who are not legal residents. Most unauthorized residents either entered the United States without inspection or were admitted temporarily and stayed past the date they were required to leave.

Unauthorized residents applying for adjustment to lawful permanent resident (LPR) status under the Immigration and Nationality Act (INA) are unauthorized until they have been granted lawful permanent residence (a green card)—even though they may have been authorized to work. Persons who are beneficiaries of Temporary Protected Status (TPS) are not technically unauthorized.

In California, the unauthorized or undocumented resident immigrant population includes individuals who are not U.S. citizens and do not have legal resident status. This encompasses those who entered the country without proper inspection as well as those who overstayed their visas. Unauthorized residents in California may seek to adjust their status to become lawful permanent residents (LPRs) under the Immigration and Nationality Act (INA). However, until they successfully obtain a green card, they remain unauthorized, despite possibly having work authorization. Beneficiaries of Temporary Protected Status (TPS) in California, while not having a permanent immigration status, are not considered unauthorized because TPS provides a temporary lawful status and work authorization. It's important to note that immigration laws and policies are subject to change, and they are enforced at the federal level by agencies such as U.S. Citizenship and Immigration Services (USCIS), while states like California may have their own policies and laws that impact immigrants within their jurisdiction.