Chapter 1 - Purpose and Background
The Immigration and Nationality Act (INA) allows certain special immigrants physically present in the United States to adjust status to that of a lawful permanent resident (LPR).  The INA defines the term “special immigrant” to include various categories of noncitizens, such as religious workers, special immigrant juveniles, and employees and former employees of the U.S. government or others who have benefited the U.S. government abroad.  Most special immigrants apply for adjustment under the employment-based fourth preference (EB-4) immigrant category. 
Special immigrants are subject to many of the same eligibility requirements as applicants seeking adjustment based on a family or employment-based preference category. For example, special immigrants are subject to immigrant visa availability. That means that an immigrant visa must be immediately available when the applicant files the adjustment of status application and at the time of final adjudication.  There are, however, some differences.
While some special immigrants are allowed to file their Application to Register Permanent Residence or Adjust Status (Form I-485) concurrently with the underlying immigrant petition, most special immigrants must first receive approval of the underlying special immigrant petition before filing an adjustment application.  Furthermore, some categories require the adjustment application to be filed before a specified deadline. 
[^ 2] See INA 101(a)(27). Congress also created additional special immigrant classifications through public laws not incorporated in the INA. These unique special immigrant classifications are also discussed in this Part.
[^ 3] See INA 203(b)(4). Technically, LPRs returning from a temporary visit abroad and immigrants applying for re-acquisition of U.S. citizenship are included in the definition of special immigrant. See INA 101(a)(27)(A)-(B). However, these special immigrants are outside the scope of the EB-4 immigrant category per INA 203(b)(4). In addition, certain Afghanistan and Iraq nationals may also seek adjustment as special immigrants, however, they do not fall under the EB-4 immigrant category since they are not included in INA 101(a)(27). Instead, the authority lies in separate public laws, which also provides for separately allocated visa numbers.
[^ 4] See INA 245(a)(3). See Part A, Adjustment of Status Policies and Procedures, Chapter 3, Filing Instructions, Section B, Definition of Properly Filed [7 USCIS-PM A.3(B)]. See Part A, Adjustment of Status Policies and Procedures, Chapter 6, Adjudicative Review, Section C, Verify Visa Availability [7 USCIS-PM A.6(C)].
[^ 5] See Part A, Adjustment of Status Policies and Procedures, Chapter 3, Filing Instructions, Section C, Concurrent Filings [7 USCIS-PM A.3(C)]. Noncitizens file a Petition for Amerasian, Widow(er), or Special Immigrant (Form I-360) to obtain special immigrant classification. Special immigrant juveniles, for example, may file both underlying petition and adjustment application at the same time. They do not need to wait for the petition’s approval before filing the adjustment application, as is the general rule. See Chapter 7, Special Immigrant Juveniles [7 USCIS-PM F.7].
[^ 6] In addition to the relevant program-specific chapters, applicants should refer to the relevant regulations, corresponding form instructions, and general adjustment guidance in this part for more information on eligibility and filing requirements. See Part A, Adjustment of Status Policies and Procedures [7 USCIS-PM A] and Part B, 245(a) Adjustment [7 USCIS-PM B].