For two years prior to starting his own firm, Mark Derry worked as a Technical Assistance Specialist and Trainer for the ADA Information Center for the Mid-Atlantic Region. The Center is one of ten regional Disability and Business Technical Assistance Centers (DBTACs) established by the U.S Department of Education to provide training, information, and technical assistance on the Americans with Disabilities Act (ADA) to businesses, consumers, and state and local governments. Mark left his position with the ADA Information Center in 1999 to start a consulting firm called Eastlake, Derry and Associates - Accessibility Solutions. The firm specializes in accessibility, universal design, and ADA consulting and training.

As a small business owner in the late 70's and early 80's, Mark designed and built custom vehicles, including lift-equipped conversion vans and automobiles with hand-controls to enable people with disabilities to drive and be more independent. After becoming an amputee as the result of a motorcycle accident in 1983, he started a construction business specializing in residential remodeling and home modifications to remove architectural barriers.

In 1993, Mark went to work as an architectural barrier consultant for Action Toward Independence, a Center for Independent Living in New York State. While at the Center, Mark served three years on the State Access Codes Board, and co-founded and chaired the ADA Committee in New York. He also hosted a monthly radio talk show on disability issues called "Making Waves", and served on the Assistive Technology Advisory Board at the Westchester Institute for Human Development.

Since moving to West Virginia in 1997, Mark has been active on a local level with his wife, Jan Derry, who is the Executive Director of the Northern West Virginia Center for Independent Living. He has been appointed by two West Virginia Governors to the Statewide Independent Living Council, and has served as Chair of the West Virginia ADA Coalition. Mark has been trained and receives regular updates on the ADA by the U.S. Department of Justice, and the U.S. Architectural and Transportation Barriers Compliance Board, also called the Access Board. Mark also currently serves as a member of the Public Rights of Way Access Advisory Committee for the Access Board. For several years Mark has been an Individual Member and Affiliate Trainer, and in July 2000 was elected by his peers to the Governing Board of the National Council on Independent Living (NCIL).