Gilder was a member of the
Simplified Spelling Board. He was a leader in the organization of the Citizens' Union, a founder and the first president of the Kindergarten Association, and of the
New York Association for the Blind. Gilder was chairman of the first Tenement House Commission in
New York City. During his service on the commission, he arranged to be called whenever there was a fire in a tenement house, and at all hours of the night he risked his health and his life itself to see the perils besetting the dwellers of the tenements, in order to make wise recommendations as to legislation that would minimize these perils.
