The first association was launched (1844) in London by Sir George Williams and a group of young men in business as a place to help other young working men find God through prayer and Bible study. In 1851 the movement took root in North America. Following the lead of Montreal and Boston, a number of other cities soon formed their own YMCAs, and in 1854 the first convention of North American associations took place in Buffalo, N.Y. A world conference in Paris (1855), attended by delegates from eight nations, led to the formation of the World Alliance of Young Men's Christian Associations in the same year.

Originally focused on Bible study and religious activities, the organization, which in 2010 began officially referring to itself as "the Y," has greatly broadened its mission statement over the years, and now has branches on every continent. Ys serve 45 million people in 120 countries, and often provide inexpensive housing, meeting space for community groups, gymnasiums and pools, and child-care programs.