Bruff was an active member of the National Institute for the Promotion of Science, which eventually became part of the Smithsonian Institution. He was a member of the National Art Association, serving as the organization's secretary for a time. He was also a member of the Washington Monument Association and a lifelong Mason. In addition, Bruff was a member of the Society of the Oldest Inhabitants of Washington City. As a prominent member of the society, he was selected to give the keynote address at the city's Washington birthday celebration held at the city hall in 1874. That same year, Bruff became a founding member of the Washington Association of Engineers and Architects, a professional organization for architects and building engineers.