The Founder Members, whose number shall at no time be added to or taken away from, were Anthony C. Baines, Philip A.T. Bate, Robert Donington, Hugh Gough, Eric Halfpenny, Edgar Hunt, E. Marshall Johnson, Lyndesay G. Langwill, R. Morley-Pegge, F. Geoffrey Rendall and Maurice Vincent. The first President of the Society was Professor J.A. Westrup.

While the initial focus was on European instruments, the need to encompass `musical instruments of all kinds was soon recognised. The Galpin Society has succeeded over the years in catering for an ever-widening range of interests within the fold of organology, as well as stimulating inter-disciplinary collaboration and the fruitful exchange of ideas. Moreover, the geographical coverage of the Society's membership list has kept on spreading: no fewer than thirty-nine countries are now represented.

The Society has a worldwide membership and is open to all, of whatever nationality or country of residence. Institutions may enrol as members and enjoy all rights of representation. Membership benefits are:
- The Annual Journal, published at the end of the subscription year, contains articles, reviews, notes and queries on all aspects of musical instruments. A Research Grant is offered to members, in anticipation of an article suitable for inclusion in the Journal.
- The Galpin Society Newsletter is issued to members, usually three times a year. It publicises future activities, reports on recent activities, lists new publications, announces organological conferences and other meetings, and carries requests for information.
- The Society organises from time to time symposia and other functions. Visits are organised to instrument collections worldwide: recent visits have been made to Brussels, Hamburg, The Hague, Lisbon, Leipzig, Vienna, Berlin, Stockholm, Munich and Nuremberg, Basel, Paris, Budapest, Brussels, Moscow and Leningrad, Boston, and Rome.
- The Annual General Meeting is held in the U.K. in the summer.