Traveling while your adjustment of status is pending requires advance parole (Form I-131). Leaving the U.S. without it can be considered abandonment of your application, potentially causing it to be denied. Once advance parole is approved, you can travel and reenter legally. Carry the approval notice along with your permanent resident card or other ID documents. Travel should be temporary and planned carefully, as the Customs and Border Protection officer still has discretion at the port of entry.