At the time of Mrs. Holton’s death in 1951, Mildred Brown became President of Holton-Arms and Sallie Lurton, Class of 1923, its Headmistress. In 1963, the School moved to the River Road campus in Bethesda, Md. The expanded facilities allowed for increased enrollment, and new courses were developed to augment a strong traditional curriculum.

In 1969, Jim Lewis became Headmaster. During his tenure, greater emphasis was placed on advanced academic courses and the improvement of the facilities. Major additions included the Alice S. Marriott Library, a photography lab, an art studio, an art gallery, an infirmary, and the Advancement Center. Once again, with new facilities came new programs: the Creative Summer day camp and LEEAP, an after-school program, offering art, music, dance, and drama classes.

Charlie Lord became Headmaster in 1987. Under his leadership, the School expanded its sense of diversity and focused on ecological concerns, ethics in the professions, and service to the community. The student activities center, housing expanded dance facilities, a double gymnasium, pool, theater, rehearsal rooms for chorus and orchestra, and several classrooms, was completed in 1989.

Diana Coulton Beebe was installed as Head of School in September of 1992. During her 15 years of leadership, Holton worked to create equity for its diverse student population; develop a strong sense of community among its constituents; support a variety of learning styles; strengthen its athletic programs; enhance the curriculum in the areas of math, science, and technology; and improve faculty salaries. The School celebrated its Centennial in 2001. The Centennial Building Project—providing students with a new science wing, expanded performing arts rehearsal and performance facilities, renovated academic spaces, and a new all-weather track and field—was completed in 2003-2004.

Susanna A. Jones became Head of School in 2007. Under her leadership, Holton-Arms School achieved several milestones, including the integration of the School's multidimensional educational philosophy known as Learn Well, Live Well, Lead Well, which rests on three pillars: Diversity, Equity, Inclusion, and Belonging; Health and Wellbeing; and Global Competence. She spearheaded the Global Education program, which has been instrumental for students as they develop global competencies, skills, and habits of mind to be leaders for a better tomorrow. Renovated in the summer of 2012, the main entrance and administrative building welcome students, faculty, alumnae, and parents to the School. Along with bright natural light and soaring ceilings, the space features thoughtful architectural details that reflect the more-than-100-year history of the School. As visitors enter, they cross over Holton’s timeless School seal and beneath the cherished motto, Inveniam viam aut faciam (or "I will find a way or make one").

Holton-Arms School welcomed its eighth Head of School Penny B. Evins on July 1, 2023. Mrs. Evins has an exceptional record of building strong, lasting relationships and motivating those around her to be the best versions of themselves. Mrs. Evins brings 25 years of independent school experience to her headship at Holton. Most recently, she served as Head of School for Collegiate School in Richmond, Virginia, and St. Paul’s School for Girls in Baltimore, Maryland. Read more about Mrs. Evins.

Today, over 120 years since its founding, Holton-Arms appears to be quite different from the school than began in 1901, yet in many ways it is the same. The School continues to maintain a high academic standard. It is a place for personal involvement, a place where parents support the School by helping out in the library, on field trips, on committees of the Board, and at special functions, and a place where outstanding faculty continue to give maximum attention to individual students.