- JDG Associate Limited
- JEB Marketing
- JLCo
- John Hopkins School of Nursing
- Johns Hopkins Bayview Medical Center
- Johns Hopkins Hospital
- Johns Hopkins University
- Johns Hopkins University, School of Hygiene and Public Health
- Johnson Lambert and Company
- JTDunn Enterprises
- JZA Inc
- Kelly Press
- Kensington Park Retirement Community
- KeraLink
- King Stringfellow Group LLC
- KNOLL
- Korrigan Media International
- KSL Resorts
- Land Rcompany
- Larry King Cardiac FD
- Legg Mason
- Legg Mason Wood Walker, Incorporated of DC
- Levindale Hebrew Geriatric Center and Hospital
- LexisNexis-CIS
- LifeLogics, Inc.
- Lilly Whittaker
- Lockheed Martin
- Love and Company
- LSSI Library Systems and Services
- Luminis Health Doctors Community Medical Center
- Madison Avenue Inc.
- Magnolia Hall Nursing Center
- Mahan Rykiel Associates
- Management Solutions Plus, Inc.
- Mark Sofman
- Marshall Management Inc.
- Maryland Center for Maternal and Child Health
- Maryland Community Health System
- Maryland Department of Business Economic Development
- Maryland Department of Health And Mental Hygiene
- Maryland Department of the Environment
- Maryland Hospital Association
- Maryland Office of Tourism
- Maryland Society of Association Executives
- MasiMax Resources, Inc.
- Mass Mutual
- McKesson Bio Services
- McKinley Marketing Inc.
- Medical Professional Liability Association
- Medicine On Time