Judge William R. Greer, Jr. has always been an active member of the Charles County community.  He grew up on a farm near Welcome and has resided in Charles County his entire career.  His commitment to the community where he was raised and lives is demonstrated by the pro bono work he has provided and the non-profits he has supported throughout his career.   He has been an active member of non-profits, government boards, and civic organizations.

Judge Greer was a founding board member and secretary of the Community Foundation of Charles County, Inc., which later became the Community Foundation of Southern Maryland.  He was a member of the Board of Directors, Charles County Chapter of the American Red Cross.

Judge Greer was appointed a member of the Charles County Grants Commission and the Charles County Board of Library Trustees.  Judge Greer was the treasurer for the Charles County Board of Library Trustees, Judge Greer was appointed a member and later chair of the Judicial Nominating Commission, Fifteenth District, which recommends attorneys to the Governor for the appointment of judges.

Judge Greer was a member of the Board of Directors for the Charles County Chamber of Commerce, a member of the Charles County Chamber of Commerce Legislative Committee and Chair of the Small Business/Miscellaneous Sub-Committee for the Legislative Committee of the Charles County Chamber of Commerce.

Judge Greer was a member of the Maryland Farm Bureau, Charles County Farm Bureau, National Guard Association, National Guard Association of Maryland, 121st Engineer Association, Army Engineer Association, Military Officers Association of America, General Smallwood Chapter of the Military Officers Association of America and the Maryland Association of Justice.