The John Carroll School, established in 1964, is a private, independent, college-preparatory, co-educational Catholic school for grades 9–12, located on 87 acres (350,000 m2) in Bel Air, Maryland, USA, about 30 minutes' drive north of Baltimore, Maryland in the Roman Catholic Archdiocese of Baltimore.
The school is named after John Theodore Carroll, SJ, the first Catholic bishop and archbishop in the United States—serving as the ordinary of the Roman Catholic Archdiocese of Baltimore.
In the early 1960s Cardinal Lawrence Shehan decided to build an Archdiocesan Catholic high school on an 87-acre (350,000 m2) site in Bel Air, Harford County. The John Carroll School opened to 202 freshmen on September 9, 1964 under the leadership of Principal Rev. Raymond Wanner. From its earliest days the school was run by clergy, religious, and laity. The number of clergy and religious employed as teachers and administrative staff greatly reduced over time.
Over 750 students in grades 9–12 attend the school. John Carroll draws students from the Baltimore metropolitan area, especially Harford, Baltimore and Cecil Counties, as well as southern Pennsylvania.
 
The school's mission statement is:
At The John Carroll School, guided by the spirit of America's first Catholic Archbishop and early patriot, we cultivate in each student a love of learning, a respect for self and a sensitivity to others. Instilling Catholic values through a challenging college preparatory program, we educate the whole person: spiritually, intellectually, physically, and socially. Our secondary school community develops young men and women of moral integrity and prepares them to serve responsibly in shaping a more just and compassionate global society.
The school's current theme is "Compelling. Considerate. Uncompromising."
 
Notable alumni
Suzan-Lori Parks, playwright.
Zach Thornton, goalie for Chicago Fire of Major League Soccer.
Drew Westervelt, class of 2003. All-time leading scorer in men's lacrosse for UMBC. Drafted 4th overall in the 2007 Major League Lacrosse draft by the Denver Outlaws. Also plays for the Philadelphia Wings in the National Lacrosse League.