North American composer sites (a quick cross-section): Mark Adamo, John Adams, John Luther Adams, Timothy Andres, Lera Auerbach, Eve Beglarian, Lisa Bielawa, Derek Bermel, William Bolcom, Martin Bresnick, Anna Clyne, John Corigliano, Corey Dargel, Kyle Gann, Alexandra Gardner, Philip Glass, Michael Gordon, Judd Greenstein, Jeff Harrington, Stephen Hartke, Phil Kline, Joan La Barbara, David Lang, Tania León, David T. Little, Steve Mackey, Ingram Marshall, Paula Matthusen, Missy Mazzoli, Alex Mincek, Meredith Monk, Nico Muhly, Andrew Norman, Pauline Oliveros, Steve Reich, Terry Riley, Ned Rorem, Christopher Rouse, R. Murray Schafer, Sean Shepherd, Kate Soper, Gregory Spears, Andrew Staniland, Steven Stucky, Morton Subotnick, Augusta Read Thomas, Joan Tower, Melinda Wagner, Julia Wolfe, Charles Wuorinen, La Monte Young, Evan Ziporyn
Some notable international composers (an even quicker cross-section): Thomas Adès, Franghiz Ali-Zadeh, Louis Andriessen, Harrison Birtwistle, Pierre Boulez, Benet Casablancas, Aaron Cassidy, Raphaël Cendo, Chen Yi, Unsuk Chin, Marc-André Dalbavie, Beat Furrer, Osvaldo Golijov, Sofia Gubaidulina, Heiner Goebbels, Guo Wenjing, Georg Friedrich Haas, Oliver Knussen, György Kurtág, Helmut Lachenmann, Liza Lim, Magnus Lindberg, Tristan Murail, Olga Neuwirth, Per Nørgård, Arvo Pärt, Stefan Prins, Wolfgang Rihm, Kaija Saariaho, Esa-Pekka Salonen, Iris ter Schiphorst, Salvatore Sciarrino, Jörd Widmann, Agata Zubel
NYC ensembles: Absolute Ensemble, Alarm Will Sound, American Composers Orchestra, American Contemporary Music Ensemble, American Modern Ensemble, Amp Music, Anti-Social Music, Argento Music, AXIOM, Bang on a Can, Columbia Composers, Contemporaneous, Continuum, counter)induction, Cygnus, Ensemble Sospeso, Da Capo Chamber Players, Either/Or, Ekmeles, Electric Kompany, Ensemble Pamplemousse, Ethel, Fireworks, Flux Quartet, Glissando Bin Laden, Hotel Elefant, ICE, Interpretations, Jack Quartet, The Knights, Ljova & The Kontraband, Locrian Chamber Players, Loadbang, Lost Dog New Music Ensemble, New York New Music Ensemble, Newspeak, North/South Consonance, NOW Ensemble, Object Collection, Qubit, Red Light New Music, S.E.M. Ensemble, Sequitur, Signal, So Percussion, TACTUS, Talea Ensemble, Thing NY, TILT Brass, Victoire, Washington Square Contemporary Music Society, Wet Ink, Yarn/Wire
Non-NYC ensembles: Montpelier VT VCME Boston Boston Modern Orchestra Project, Boston Musica Viva, Sound Icon, Equilibrium Concert Series, Callithumpian Consort, Collage New Music, Dinosaur Annex, Alea III Rochester Ossia Syracuse Society for New Music Kingston Deep Listening Princeton Composers' Ensemble Philadelphia Orchestra 2001, Relâche, Bowerbird, Network for New Music Pittsburgh Pittsburgh New Music Ensemble Baltimore Peabody Camerata, Evolution DC Great Noise Ensemble, Verge Ensemble, Contemporary Music Forum Atlanta Bent Frequency Cleveland Cleveland Contemporary Players Bloomington Aguavá, IU New Music Ensemble Chicago Eighth Blackbird, ICE, Spektral Quartet, Contempo, CUBE, Dal Niente, noamnesia, MAVerick Ensemble, Accessible Contemporary Music Allendale MI GVSU New Music Ensemble Lansing Musique 21 Minneapolis Zeitgeist Milwaukee Present Music Iowa City Center for New Music Kansas City newEar, Black House Collective Nashville Alias Music, Intersection Memphis Luna Nova Houston Musiqa Dallas Voices of Change Austin UT New Music Omaha/NYC ANALOG Arts Ensemble Boulder Pendulum Seattle Seattle Composers' Salon, Seattle Chamber Players Portland Music Population Orchestra, Third Angle San Francisco Other Minds, San Francisco Contemporary Music Players, Kronos, Earplay, OOGOG, Paul Dresher Ensemble, sfSound, Edmund Welles, Left Coast Chamber Ensemble, San Francisco Composers Chamber Orchestra Santa Cruz New Music Works Los Angeles E.A.R. Unit, Monday Evening Concerts, Jacaranda, WasteLAnd Music, What's Next Ensemble, Gnarwhallaby, People Inside Electronics, CalArts, Southland Ensemble, The Wulf, Hocket, Formalist Quartet, wildUP, Ensemble Green San Diego NOISE Davis Empyrean Ensemble Phoenix Crossing 32nd Street
Composer lists: Thomas Moore
Collectives: Bang on a Can, Common Sense, Minimum Security, Pulse Optional
NYC new music calendar: SoundArt