The roots of Loudoun Country Day School go back to the summer of 1952, when Mrs. J. Churchill Newcomb and Mrs. William J. McDonald called a meeting at the Purcellville Library. From this meeting began the final planning for a first school year at Loudoun Country Day School in 1953-1954: seven students and a teacher who met in a room in the Old Community College Building on Market Street in Leesburg.

In 1957, through the generosity of Mrs. Elizabeth Rust Brown, 5.4 acres and a farmhouse on Fairview Street in Leesburg were made available to the school. In 1959, LCDS was incorporated. Loudoun Country Day School achieved accreditation through VAIS (Virginia Association of Independent Schools) in 1970 and became a member of AISGW (Association of Independent Schools of Greater Washington) in 1976 when the student enrollment was 136.

In 2003 and 2004, LCDS celebrated its 50th anniversary; in May a reception was held and Mrs. Edith Newcomb, the first headmistress, attended, at age 87.

In 2006, the school purchased 70 acres at the Red Cedar development off of Evergreen Mills Road.

On March 31, 2008, Loudoun Country Day School held its official groundbreaking ceremony on the new campus location, with Governor Timothy M. Kaine attending and speaking. On July 9, 2009, after 52 years on Fairview Street, LCDS moved to the new campus here at Red Cedar off Evergreen Mills Road.

LCDS held its official ribbon-cutting ceremony on September 13, 2010. Board Chair Fred Schaufeld, former board member Brad Brown, and current board members attended, as well as Headmaster Randy Hollister, faculty, staff, and students.

On May 12, 2012, the lower school wing was dedicated to Fred and Karen Schaufeld, at an event honoring them at the Red Cedar campus. Their years of service to the school, as well as their vision for the new campus and financial support of that endeavor, were recognized at an unveiling of the words on the side of the lower school building, “Fredrick D. and Karen G. Schaufeld Lower School.” Former board members, current board, family and friends, as well as staff and faculty, were present at this important occasion, planned by headmaster Dr. Randy Hollister.

The years 2010 through 2014 were consecutive, record-setting years for opening day enrollment, increasing from 285-319 during those years.

Loudoun Country Day School completed a rigorous ten-year reaccreditation in November 2013, through VAIS (Virginia Association of Independent Schools) and received the official notice of reaccreditation in August of 2014.

LCDS began a BYOT (Bring Your Own Device) initiative in 2013, implemented in sixth through eighth grade. In 2014, the BYOD program was extended to 4th and 5th grade.

In 2015, Loudoun Country Day School inaugurated a program for three-year-olds, expanding to preschool through eighth grade.