Family reunification, also known as family-based immigration or family sponsorship, is at the heart of immigration policy in the United States. It allows U.S. citizens and lawful permanent residents (green card holders) to petition certain family members to come and live in the United States. The goal is to promote family unity and to allow families to be united in the United States.

Immediate relatives of U.S. citizens—such as spouses, unmarried children under 21 years old, and parents—have special immigration priority and can as a rule immigrate to the U.S. sooner than other categories of family-sponsored immigrants. Other family members, such as adult children, siblings, and married children, fall into different priority categories and may face longer wait times due to annual quotas on family-sponsored visas.

The process essentially involves the U.S. citizen or lawful permanent resident filing a petition (Form I-130) with United States Citizenship and Immigration Services (USCIS) for the family member. Once the petition is approved, the family member may need to wait for an available visa before they can immigrate to the United States. The number of visas can vary depending on the relationship of the family member to the sponsor and the country of origin.

Family-based immigration has been a cornerstone of U.S. immigration policy for decades and continues to contribute a significantly in shaping the demographic construct of the United States. However, like other aspects of immigration policy, it has been subject to debate and legislative changes over through the years.