"Porterfield" 's next assignment was screening escort carriers during the Marianas invasion. The group sortied from Pearl Harbor 30 June, with "Porterfield"s group of jeep carriers furnishing air coverage for the advance. The group arrived off Saipan 15 June and enemy air attacks began shortly thereafter. "Porterfield" stayed with the force, rescuing two pilots, before being sent to Eniwetok 1 July for dry-docking. After her repairs, the ship reached Saipan again 11 July and operated with the carrier screen until sent to Guam early in August.