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 Delaware, as in all states, the definition and treatment of unauthorized or undocumented resident immigrants are primarily governed by federal law, specifically the Immigration and Nationality Act (INA). Unauthorized immigrants are those who have entered the United States without proper inspection or have overstayed their visas. These individuals are not considered legal residents. Unauthorized immigrants in Delaware may apply for an adjustment of status to become Lawful Permanent Residents (LPRs), but they remain unauthorized until they are granted a green card. It is important to note that during the application process, some may be granted work authorization. Additionally, individuals with Temporary Protected Status (TPS) in Delaware are not considered unauthorized, as TPS is a temporary legal status granted to eligible nationals of designated countries affected by armed conflict, natural disaster, or other extraordinary conditions.