St. Margaret's was founded in 1979 by the Reverend Ernest Sillers. The school began with only 79 students in kindergarten through grade six. It was named in honor of the 11th-century Queen Margaret of Scotland, the patron saint of education. The significance of this name is reflected in many St. Margaret's traditions, such as the use of bagpipes in formal ceremonies, along with their athletic team nickname, the Tartans. St. Margaret's opened an Early Childhood Development Center in 1981 and its high school in 1982. By 1985, students were enrolled in grade levels preschool through 12. In 1986, St. Margaret's brought in Markham B. Campaigne as its second headmaster. During his 17-year tenure, St. Margaret's grew to serve over 1,200 students and expanded to a campus. It is now included in Princeton Review's top 444 private schools in the United States book. In 2004, Marcus Hurlbut became the new Headmaster of SMES. In 2013, William Moseley became headmaster.
Academics
St. Margaret's offers courses in core subjects, as well as other subjects through electives. Theater, art, music and other subjects are available to be taken in addition to the main subject. There are 26 Advanced Placement courses offered in history, math, science, art, language, theatre, music and other subjects. In addition to Advanced Placement courses, St. Margeret's offers honors courses throughout their various subjects. The variety of courses gives students the opportunity to excel to the best of their ability.
Athletics
St. Margaret's sports teams are called the Tartans, and they compete as members of the Academy League in the CIF Southern Section. In 2006, the Tartan football team finished 14-0 and won the CIF-SS Northeast Division championship. and in 2008 the Girls' Varsity Tennis Team were the Academy League and CIF Champions, defeating league rival Sage Hill in the finals to finish off a 23-0 winning streak. The 2010-2011 Athletics year was one of the most successful, with 4 CIF Championships in Boys Cross Country, Girls Volleyball, Girls Tennis, and Girls Soccer teams. Additionally, the Boys Cross Country team won the CIF Division 5 State Championship in 2010, 2011, and 2018. St. Margaret's Athletic Program has also been recognized as one of the Top 5 out of all Divisions in Orange County. The varsity girl's soccer program won 4 CIF championships in 2006, 2011, 2012, and 2014. The St. Margaret's football team won the Southern California small-school division championship in the 2014-2015 season. The 6th to 12th grade sports consist of equestrian, golf, basketball, volleyball, soccer, cheer, dance, lacrosse, general PE, and much more. Some sports are separated by gender like volleyball or basketball, but some sports are co-ed such as soccer or dance.
Campus
In 2007, St. Margaret's completed construction on the DeYoung Family Math and Science Center. In 2011, St. Margaret's constructed a performing arts center, which includes the Hurlbut Theater and houses the music, dance, and theatre departments. A new middle school was constructed in 2015. St. Margaret's has 2 gyms: the Campaigne Center, used by lower schoolers, and the Pasternack Field House, used by middle and upper schoolers. The Pasternack Field House was completed in 2007. There is a middle school field and a main football field, used by members of the high school. The campus covers 22 acres.
