The Ninety-Nines: International Organization of Women Pilots, also known as 99s, was founded on November 2, 1929 at Curtiss Field, Valley Stream, New York for the mutual support and advancement of women pilots. All 117 women pilots licensed at the time were invited and the group is named for the 99 of them who attended the meeting or expressed an interest in forming a group. Charter members include Amelia Earhart, Fay Gillis Wells, Ila Loetscher, Phyllis Fleet, Betty Gillies, Candis Hall, Louise Thaden, Ruth Nichols, Phoebe Omlie, Mary Goodrich Jenson, Opal Kunz and Mildred Stinaff. The first president elected in 1931 was Amelia Earhart. Other famous members include Jackie Cochran, Elsie MacGill, Bobbi Trout, Pancho Barnes, Patty Wagstaff, Jeana Yeager, Sheila Scott, Eileen Collins, Shirley Zillig, Bonnie Gann, Linda Godwin and Nancy Bird Walton.

Charter Member Margaret Thomas "Tommy" Warren believes she might have been the youngest Charter Member of the 99’s- only 17 when she joined. She was not present at the first gathering of women aviators on Long Island in October 1929, but did go to New York with Frances Harrell for the second meeting on December 14 at the home of Opal Kunz, and was appointed to represent Texas.

Currently, the organization has 5,230 members in thirty countries. The mission of the Ninety-Nines is to promote world fellowship through flight; to provide networking and scholarship opportunities for women and aviation education in the community; and to preserve the unique history of women in aviation. The Ninety-Nines, Inc is a non-profit 501(c)3 organization. The organization is divided into "sections" that are part of geographical areas covering several states in the U.S., provinces in Canada and even countries. Chapters are the smallest grouping, falling under their geographical "sections".

The Ninety-Nines' 'Amelia Earhart Memorial Scholarship Fund' (AEMSF) program assists in funding flight training for both recreational and career track female pilots by awarding a scholarship for an entire pilot certificate or rating to qualified members. The AEMSF "new Pilot Award" helps an aviatrix finish her Private Pilot training. In addition to the AEMSF program, many individual chapters of the Ninety-Nines give their own flight scholarships to benefit local aviatrixes. Aspiring professional pilots can find career guidance and mentors in the Ninety-Nines "Professional Pilot Leadership Initiative" program.

Ninety-Nines members support the goals of the organization by being active in numerous aviation activities including: aviation education seminars in the community; air racing, from the Powder Puff Derby to the Palms to Pines and the Air Race Classic; airmarking by volunteering their time to paint airport names, compass rose symbols and other identifications on airports and the National Intercollegiate Flying Association (NIFA), most regional and national NIFA competitions have "99s" on their panel of judges.

Their international headquarters building on Will Rogers World Airport in Oklahoma City, OK is home to the 99s Museum of Women Pilots. Museum artifacts include historical papers, personal items, video and oral histories, photos, memorabilia and other notable artifacts from famed aviatrixes from around the globe. The museum collection and exhibits provide insight into the role women pilots played in the development of aviation and their historical footprint.

The Ninety-Nines are also owners and custodians of the Amelia Earhart Birthplace Museum in Atchison, Kansas. The birthplace and early childhood home of early aviatrix Amelia Earhart was declared a National Historic site and has been returned to its turn-of-the-century condition by the "99s", and features an abundance of personal and family memorabilia.