"Aging Out" arises in some situations when a child nearing 21 years of age applies for adjustment of status or consular processing. In many instances, alien children are eligible for family-based immigration benefits if they are the children of a U.S. citizen or permanent residents, or the children of a beneficiary of an immigrant petition. Under immigration law, a child is defined as an unmarried person under the age of 21. In the past, if a child applicant or beneficiary reached the age of 21 while their application for adjustment of status or application for immigration visas was still pending, that child lost eligibility for a Green Card. Children who turned 21 before their applications were decided therefore "aged out". As a result, they no longer qualified for many of the immigration benefits they originally petitioned for before they were 21. 

Congress, however, recognized that many potential immigrants were aging out before their petitions could be approved due to long wait times and visa backlogs. In 2002,Congress passed the Child Status Protection Act (CSPA), which now protects a beneficiary’s child status when he or she ages out due to excessive waiting time for visas.