The 1978 USC Trojans football team represented the University of Southern California in the 1978 NCAA Division I-A football season. Following the season, the Trojans were crowned national champions according to the Coaches Poll. While Alabama claimed the AP Poll title because it had defeated top-ranked Penn State in the Sugar Bowl, the Trojans felt they deserved the title since they had defeated Alabama and Notre Dame during the regular season, and then Michigan in the Rose Bowl. Both USC and Alabama ended their seasons with a single loss.
This would be the last national championship won by the Trojans until 2003.
All 22 starters played in the NFL.