The 2018 edition of the Monarchs did the unthinkable. After graduating much of the talent from the 2017 national championship team, they went out and won a second consecutive national championship. On the field, Mater Dei outscored its five pre-league opponents 217 to 38, including Florida’s IMG Academy, which had probably the greatest collection of high school talent in the country. The Monarchs then went 4-1 in league play, losing only to league rival St. John Bosco in a game delayed one night by a violent lightning storm.
In the playoffs, Mater Dei rolled over Valencia, Mission Viejo and Corona Centennial by an average score of 49-12, and then they gained revenge against St. John Bosco in the Division 1 championship game when they beat the Braves 17-13.
In the State Open Division championship game, Mater Dei defeated De La Salle for the second straight year by a score of 35-21, leading most of the national polls to again crown the Monarchs as their 2018 national champions.