This booklet provides a history of the role played by extracurricular activities in American secondary education, summarizing their objectives, principles, and problems, and classifying their types. The student-activity concept is traced through four stages of historical development in the United States. Noting that the objectives of cocurricular activities keep pace with the changing activity goals of schools, the authors then compare five compilations of cocurricular objectives specified by five research studies conducted between 1931 and 1975. Turning from history to the needs of present-day school programs, the authors provide school leaders with 16 principles for guidance in achieving educational goals. A taxonomy of extra-class activities is supplied to aid local schools in assessing the breadth of their programs. Finally, the common problems in extracurricular activities are analyzed: student participation, sponsorship and faculty participation, and scheduling of activities. (JW)