Although the youngest of the world-wide service clubs, Lions International is by far the largest, with more than 1,415,600 members in 42,732 clubs in 178 countries on six continents. Lions International, officially named The International Association of Lions Clubs, was formed on June 7, 1917. After a merger of business luncheon clubs in Chicago with the Lions Clubs of Indiana, Melvin Jones, a young Chicago insurance agent, is considered the Founder of Lionism and served for more than forty years as the first General Secretary of the national organization.

The first national Lions convention was held on October 8, 1917, in Dallas, Texas, with 23 clubs participating with a total of 36 delegates. They elected Dr. William P. Woods of Indiana as their first president. Guiding force and founder Melvin Jones named acting secretary, thus began an association with Lionism that only ended with his death in 1961. International Conventions are now held annually during July with more than 15,000 Lions from around the world voting as official delegates. The 1997 Convention will be held in Philadelphia, Pennsylvania.

That first convention also began to define what Lionism was to become. A constitution and by-laws were adopted, the colors of purple and gold approved, and they started developing Lionism's Objectives and Code of Ethics.

One of the objects was startling for an era that prided itself on mercenary individualism, and has remained one of the main tenets of Lionism ever since. "No Club" it read, "shall hold out the financial betterment of its members as its object."

Community leaders soon began to organize clubs throughout the United States, and the association became "international" with the formation of the Windsor, Ontario, Canada Lions Club in 1920. Clubs were later organized in China, Mexico, and Cuba. By 1927, membership stood at 60,000 in 1,183 clubs.

In 1935, Panama became home to the first Central American club, with the first South American club being organized in Columbia the following year. Lionism reached Europe in 1948, as clubs were chartered in Sweden, Switzerland, and France. In 1952, the first club was chartered in Japan.

Since then, the association has become truly global, with clubs in more than 178 countries and geographical areas worldwide.

The Association is a non-profit corporation governed by a volunteer Board of Directors. All of Lionism serves under the Lions Code of Ethics and the Clubs are governed by the Objects of Lions Clubs International.

Since the International Convention of 1920, when Helen Keller challenged the Lions to become "Knights of the Blind in the battle against darkness," sight conservation has been a high priority of Lions service. The first white cane was invented by a Lion, and the first school to train guide dogs for the blind was started by Lions. Lions established the first eye banks to harvest corneal tissue to give sight to those who suffered blindness because of injury or disease. In 1993, the efforts of Lions culminated in the Lions SightFirst Campaign, a fundraising drive to raise funds to restore the sight of the 32,000,000 people in the world who have curable blindness, and to prevent blindness from occurring to an equal number who might lose their sight in the next 25 years. The campaign, which raised more than $146 million, will accomplish those goals around the world.