Organizations [ classified by lineage, when possible ]

Gurdjieff Foundation/Institut/Society lineage

Gurdjieff Institut/Society/Foundation: World´s largest organization with direct lineage back to Gurdjieff himself, organized during the early 1950s

Australia / Sydney
Canada / Toronto
Denmark
Finland
Ireland
Netherlands
Norway
UK / London
UK / Scotland
USA / Arizona
USA / Austin - San Antonio
USA / Florida
USA / Illinois
USA / Indiana
USA / Kansas City
USA / Los Angeles
USA / Massachusetts
USA / Minnesota
USA / New York
USA / Ohio
USA / Orange County
USA / Philadelphia
USA / Oregon / Portland
USA / Rochester Folk Art Guild
USA / San Diego
USA / San Francisco / California
USA / Houston, Texas
USA / Washington D.C.
USA / Washington State
USA / Western Massachusetts
USA / Western North Carolina

Institut pour le Développement Harmonique de l´Homme

Institut pour le Développement Harmonique de l´Homme: Conferences, working groups, concerts and seminars
Le Centre Gurdjieff: Le Centre Gurdjieff

Conferences

All & Everything: Annual All & Everything International Humanities Conference
Armenia-Gurdjieff Conference: The Life and Work of G.I. Gurdjieff: Caucasian Influence in Contemporary Thought and Culture

Boris Mouravieff & Esoteric Christianity lineage

Association Boris Mouravieff: L'Association Boris Mouravieff, créée en mai 2000, se donne comme finalité principale de veiller à la continuité de la publication de Gnôsis.
Early Christian Thought: Praxis Research Institute

J.G. Bennett lineage

Claymont Society for Continuous Education: Society founded by John Bennett at the end of 1974
The DuVersity: Organization directed by Anthony G.E. Blake
The DuVersity / UK: DuVersity UK

W.A. Nyland lineage

Institute for Religious Development: Gurdjieff's Teaching In the Groups of Willem A. Nyland

USA / Los Angeles
USA / New York City & Warwick
USA / Northern California
USA / Philadelphia
USA / Tucson
USA / Washington State

P.D. Ouspensky lineage

The Study Society: The Society for the Study of Normal Psychology at Colet House
Ouspensky Foundation: The Ouspensky Foundation, founded on the 26th of June 1997 in Amsterdam

Rina Hands lineage

The Bradford Gurdjieff Society: Founded by J.G. Bennett in 1949 and led for over 40 years by Rina Hands.

More organizations...

Authentic Breathing: Formerly Mountain Wind
Bennett Books Publishing & Sales: Keeping alive the literary and spiritual legacy of J.G. Bennett (1897-1974)
Church of Conscious Harmony: Contemplative Christian community by Tim and Barbara Cook, Texas, USA.
Discovery Institute: Institute by Frank Crocitto, New Paltz, New York, USA
Gurdjieff Austin: Gurdjieff Austin website
Fourth Way® Gurdjieff Ouspensky School: Fourth Way® School, London, UK
Gurdjieff Society / Greece: Gurdjieff Greece website
Gurdjieff Society / Hungary: Gurdjieff Hungary website
Gurdjieff.de: Der vierte Weg
Gurdjieff Dominican Group: Fourth Way school in the Dominican Republic
Gurdjieff Legacy: AreteTelos Society
Gurdjieff Studies Ltd, London: Group constituted in 1994 by James Moore
Gurdjieff-Ouspensky Centers: Also known as Fellowship of Friend
Institute for the Development of the Harmonious Human Being: IDHHB - Organization headed by E.J. Gold
Institute of Universal Energies: Principal : Ian Phillips Lawrence
Kesdjan Foundation: Foundation directed by Kevin Roberts
Quantum Metaphysics Institute: In Pursuit of Psychological and Spiritual Realities by Derek Lamar
Search at Northeon Forest: Community directed by Paul H. Beidler
Schule des Augenblicks: Die deutschen Gurdjieff-Seiten von Bruno Martin
Sirian Cultural Society: Art, Music, Psychology and Cosmology in the Tradition of Objective Science
Society for The Inner Development of Man (UK): Group inspired by Ronnie Stennett-Willson
Sojourner Institute: Institute directed by Shirra Meiklejohn-Wilson
Summa Foundation for Mindful Living: Community in Pennsylvania, USA
systematics.org: Formerly UniS Institute founded in 1985 by Saul Kuchinsky
Tao House: Community by Sensei Sequoia
Tayu Meditation Center: Community founded in 1976 by Robert Daniel Ennis

Warnings...

False Schools and Sham Religions
Errors on the Way
Degenerate Players Misrepresenting the Work
Brainwashing and Thought Control
Eliminate Cult Abuse by Stella Wirk
Fellowship of Friends by Rick Ross