In September 1958, the predecessor to today's CSM, Charles County Junior College, began evening classes at La Plata High School.

[5] In 1968, Charles County Community College began construction of the Career Education and Administration Building on what is now the main CSM campus in La Plata, Maryland.

[7] The Charles County facilities include the La Plata Campus in La Plata, the Regional Hughesville Campus in Hughesville, the Center for Transportation Training in Waldorf, and the Velocity Center at Indian Head.

[10] The Community College of St. Mary's County was established in 1978 at Great Mills High School.

[12] The B Building is a two-story 30,000-square-foot (2,800 m2) construction, which includes student services, seven computer labs and classrooms, the newly expanded wellness center, the Nuclear Energy Training Center, and is the college's first LEED certified building with four green roofs.

[13] On February 27, 2013, the College of Southern Maryland announced it had purchased 74 acres in Hughesville to build another campus.