In California during the twenties, high school fraternities were in their heyday. Educators were concerned with the pernicious side of these groups and sought some means of replacing them with more wholesome activity for youth. The idea of junior service clubs was broached in 1924 by two men of the Sacramento Kiwanis Club. It would be similar to Kiwanis and have its own classifications based on school interests. They hoped that the club would provide vocational guidance to boys in high school. After getting approval, eleven charter members comprising the first Key Club met for the first time in May of 1925. As the experience of Key Club grew, a noticeable trend toward expanding the original purpose was found possible. The club was soon an official service organization for the whole school.

Key Club is an international student-led organization that provides its members with opportunities to perform service, build character, and develop leadership. With over 260,000 members from approximately 6,000 clubs in over 30 countries, the organization is unique because a local Kiwanis club sponsors a local Key Club. As well as a local level, Key Club functions on a district and international level as well. The Pennsylvania District, chartered in 1947, has over 12,000 members with over 200 clubs.