Special Olympics is the world's largest sports organization for children and adults with intellectual disabilities, providing year-round training and activities to 5 million participants and Unified Sports partners in 172 countries. Special Olympics competitions are held daily, all around the world—including local, national and regional competitions, adding up to more than 100,000 events a year. Like the International Paralympic Committee, the Special Olympics organization is recognized by the International Olympic Committee; however, unlike the Paralympic Games, its World Games are not held in the same year nor in conjunction with the Olympic Games.

The Special Olympics World Games is a major event put on by the Special Olympics committee. The World Games generally alternate between summer and winter games, in two-year cycles, recurring every fourth year. The games were first held on July 20, 1968, in Chicago, Illinois, United States, with about 1,000 athletes from the U.S. and Canada. At those first games, honorary event chair Eunice Kennedy Shriver announced the formation of the Special Olympics organization. International participation expanded in subsequent games. In 2003, the first summer games held outside the United States were in Dublin, Ireland, with 7000 athletes from 150 countries. The most recent Summer Games were hosted in Berlin, Germany, between June 16 to 25, 2023.

The first World Winter Games were held in 1977 in Steamboat Springs, Colorado, US. Austria hosted the first Winter Games outside the United States in 1993. The most recent Special Olympics World Winter Games were held in Turino, Italy from March 8, 2025, to March 15, 2025. During the World Winter Games of 2013 in Pyeongchang, South Korea, the first Special Olympics Global Development Summit was held on "Ending the Cycle of Poverty and Exclusion for People with Intellectual Disabilities", gathering government officials, activists and business leaders from around the world.

Eunice Kennedy Shriver, sister of US president John F. Kennedy, believed that people with intellectual disabilities could be happy and live meaningful lives. Eunice founded the Special Olympics to positively change attitudes towards mentally handicapped people. In June 1963, Kennedy Shriver started a day camp called Camp Shriver for children with intellectual and physical disabilities at her home in Potomac, Maryland. The camp sought to address the concern that disabled children had very little opportunity to participate in organised athletic events. With Camp Shriver as an example, Kennedy Shriver, then head of the Joseph P. Kennedy Jr. Foundation and a member of President John F. Kennedy's Panel on Mental Retardation, promoted the concept of involvement in physical activity and other opportunities for people with intellectual disabilities. Camp Shriver became an annual event, and the Kennedy Foundation gave grants to universities, recreation departments, and community centers to hold similar camps.

Also in the early 1960s, Kennedy Shriver wrote an article in the Saturday Evening Post, stating that her sister, also President John F. Kennedy's sister, was born with intellectual disabilities. Her sister, Rosemary Kennedy was slow to learn, suffered seizures and mood swings. Her mother was told by doctors that Rosemary's situation was hopeless. In the early 1940s, Rosemary was prescribed a lobotomy, which left her incapacitated. This frank article about the President's family was seen as a "watershed" in changing public attitudes toward people with intellectual disabilities. Rosemary's disability provided Kennedy Shriver with an overall vision that people with intellectual disabilities could compete and at the same time unify together in public. It has often been said that Rosemary's disability was Eunice's inspiration to form Special Olympics (as the movement came to be called); Eunice told The New York Times in 1995 that that was not exactly the case. "The games should not focus on one individual," she said.

In 1958, Dr. James N. Oliver of England had conducted pioneering research, including a ground-breaking study showing that physical exercise and activities for children with intellectual disabilities had positive effects that also carried over into the classroom ("The Effects of Physical Conditioning Exercises and Activities on the Mental Characteristics of Educationally Sub-Normal Boys, British Journal of Educational Psychology, XXVIII, June 1958). Oliver in 1964 served as a consultant to Camp Shriver.

Let me win but if I cannot win, let me be brave in the attempt

The 1964 research of Dr. Frank Hayden, a Canadian physical education professor from London, Ontario, demonstrated that intellectually disabled people can and should participate in physical exercise. He believed that the benefits of such activity would be seen in all areas of the athletes' lives. With the help of a local school that offered space in its gym, Hayden started one of the first public organised sports programs, floor hockey for individuals with intellectual disabilities, in the fall of 1968. In the mid-1960s, Hayden also developed an idea for national games, and his work brought him to the attention of the Kennedy Foundation. He shared his ideas for national games, while taking a teaching sabbatical and working for the foundation.