Organizers
- M&M Multisport Club
- M2M
- MAC Olive Grove School
- Mackay Triathlon Club
- Mackintosh Academy Boulder
- Macomb Community College
- MacPhail Center for Music
- Macphail Woods Ecological Forestry Project
- Mac's National Soccer School
- MacTheatre
- Mad Hatters Theatre School
- Madison Academy
- Madonna Learning Center, Inc
- Madras Aquatic Center Recreation District
- MAEA- Windham Raymond Adult Education
- MAEA-Bonny Eagle Adult Education
- MAEA-MSAD1 Adult & Community Education
- MAEA-Spruce Mountain Adult Education
- Main Street Marathon, LLC
- Mainly Marathons
- Majestic Empire Foundation
- Maker Lab Extreme
- Malibu Water Polo Camp
- Manchester Sailing Association
- Manfred Kapper Soccer Inc. (dba Kapper Soccer)
- Manhattan Arts Center
- Mansfield Activities Center
- Maplewood Enrichment Center Inc.
- MAPS-Seattle
- MAPS-Snohomish
- Marana Parks and Recreation
- Maranacook Adult Education
- Marblehead Little Theatre
- Mariemont City Schools
- Marine Science Institute
- Marinwood Community Services District
- Mark Morris Dance Group
- Marksman Group of SC
- Marshfield Parks and Recreation Department
- Marshwood Adult & Community Education
- Martha's Vineyard Adventure Camp
- Marty Smith Sports Camps
- Maryville Alcoa Blount County Parks and Recreation Commission
- Más deporte
- MASK Swim Team
- Mason Community Arts Academy
- Master Automotive Training
- Mater Dei High School Camps
- Mavs Academy Basketball Club
- Max Adventure
