Kiwanis International (/kɪˈwɑːnɪs/ ki-WAH-nis) is an international service club founded in 1915 in Detroit, Michigan. It is headquartered in Indianapolis, Indiana, United States, and is found in more than 80 nations and geographic areas. In 1987, the organization began to accept women as members. Kiwanis and its affiliated clubs have more than 600,000 members. Kiwanis clubs raise over $100 million each year and report over 18.5 million volunteer hours to strengthen communities and serve children.

Kiwanis International is a volunteer-led organization led by a Board of Trustees with 19 members, including 15 trustees, four elected officers, and an executive director. The trustees are elected for three-year terms, with five trustees being elected each year. According to the bylaws, nine trustees are elected from the US and Pacific Canada Region, one trustee from the Canada and Caribbean Region, two trustees from the European Region, two trustees from the Asia-Pacific Region, and one trustee elected "at large" from any region other than the US and Pacific Canada Region. The elected officers included (in order of progression): the vice president, president-elect, president and immediate past president. These officers, along with the United States and Pacific Canada Region trustees, are elected at the annual convention of Kiwanis International. All trustees and officers are unpaid volunteers. The executive director is a full-time employee who is responsible for the organization's paid staff and serves as a non-voting member of the Board.

There are seven regions in Kiwanis: Africa; Asia-Pacific; Canada and Caribbean; Europe; Latin America; Middle East; and the United States and Pacific Canada. The United States and Pacific Canada Region incorporates the 50 states of the United States as well as British Columbia and the Yukon Territory of Canada.

There are fifty-three administrative areas called districts. District boards typically consist of a governor-elect, governor, immediate-past governor, secretary, treasurer, and several trustees or lieutenant governors. Districts are further divided into service areas called divisions, comprising 5 to 20 clubs and headed by a lieutenant governor. Clubs have boards consisting of a vice president (and/or president elect), president, immediate past president, secretary, treasurer, and typically about five directors. At both the district and club level, the secretary/treasurer may be combined by one person and may be a volunteer or a paid employee; all other positions are unpaid.

The name “Kiwanis” was coined from the Ojibwe language expression derived from the word giiwanizi meaning to "fool around": ningiiwaniz, which is found in the Baraga Dictionary as "nin Kiwanis", meaning "I make noise; I am foolish and wanton" or "I play with noise". Although Random House Dictionary states that it comes from one of the Algonquian languages and means "to make oneself known", in Ojibwe and other related Algonquian languages, this expression would be gikendami'idizo.^{[citation needed]} Whatever the original meaning may be, the organization's founders translated it as "We Build", which became the original motto of Kiwanis. In 2005 the organization chose a new motto, "Serving the Children of the World". Members of the club are called Kiwanians.

"Kiwanis is a global organization of volunteers dedicated to improving the world, one child and one community at a time."

Kiwanis' motto is "Serving the Children of the World." The original motto was "We Trade". A new motto of "We Build" was adopted during the 1920 International Convention and represented Kiwanis for more than 80 years.

The six permanent Objectives of Kiwanis International were approved by Kiwanis club delegates at the 1924 Convention in Denver, Colorado.