With thousands of Marines joining, changing duty stations, and being discharged from the Corps, 0170 Personnel Officers work to ensure the accuracy of all Marines' personnel records. These 0170's are the Marine Corps' subject-matter experts on all things related to personnel administration. Many Personnel Officers, affectionately called PersO's (pronounced purse-oh), work in the Installation Personnel Administrative Center's as director, assistant director, or head of an Inbound or Outbound section. With one IPAC per base, these PersO's are responsible for administrative accuracy of thousands of Marines at any given time.

Personnel Officers function as special staff advisors to commanders and staffs on all personnel administration functions and operations. They are subject matter experts on all personnel administration disciplines and their application across the spectrum of military operations. They formulate plans, policies, and procedures pertaining to personnel administration operations at all levels of the Operating Forces and the Supporting Establishment.