a general reference work for home, school, and library, designed primarily for children and young people in the upper elementary grades and high school and for family use.

In the late 20th century Compton's contained about 5,200 main articles in 25 volumes. A 26th volume, the Fact-Index, included more than 26,000 shorter articles on subjects that might not be fully treated in the main articles, 63,500 brief entries, and nearly 300,000 references to main-entry text and cross-references within the Fact-Index.

Compton's was called a “pictured” encyclopaedia because it was the first to use photographs and drawings on the same pages with the text. With the 1968 edition the word Pictured was removed from the title; the encyclopaedia remained nevertheless profusely illustrated, with recent editions containing more than 22,500 illustrations, including about 2,000 maps. Compton's is kept up-to-date by means of continual revision of the 26 volumes and the annual publication of Compton's Yearbook.

For use on personal computers, a single-disc CD-ROM (compact disc read-only memory) version of Compton's was first released in 1990. Entitled Compton's MultiMedia Encyclopedia, this first true multimedia encyclopaedia contained lavish graphics, animation, and sound. Compton's MultiMedia Publishing Group was acquired by the Tribune Company, a Chicago-based media firm, in 1993 and merged into SoftKey International Inc. in 1996.