Billie Hagen Schnabel, 36, freelance writer who was active in civic and historical projects in College Park, died of cancer Sunday in the Washington Hospital Center.

Mrs. Schnabel was a founder of the Old Town College Park Preservation Association in 1978 and was the association's president at the time of her death. She also edited its newsletter.

In early 1979, she was appointed to the Prince George's County Committee of the Maryland Historic Trust. Since January of this year, she represented College Park on the historic sites and district plans committee of the Prince George's County Council.

She had been a free-lance writer since 1976 and had contributed articles on land use policy to The Washington Post and the Prince George's Journal.

She was a member of the American Civil Liberties Union, Common Cause, and the Maryland Historical Society.

Mrs. Schnable was born in Ashville, N.C., and reared in the Washington area. She was a 1966 graduate of the University of Maryland where she earned a bachelor's degree in secondary education, specializing in English and art.

She taught high school English in San Antonio while her husband, Robert H. Schnabel, was stationed there in the Air Force. They later lived in the Boston area before moving to College Park in 1971.

For the next two years she taught art at the Kelly Miller Junior High School in Washington. She then developed an arts program for school playgrounds which she helped direct in Prince George's schools for the Maryland-national Capital Park and Planning Commission.

In addition to her husband, survivors include a son, Robert P., of College Park, and her mother, Margaret Hagan of Camp Springs.

The family suggests that expressions of sympathy be in the form of contributions either to the St. Francis Burial Society in Washington, or to the Old Town College Park Preservation Association, 4710 Norwich Ave., College Park, 20740.