For the purpose of this page, "children's series books" are sets of three or more books with at least one character that is the same in all the books. Most often, each volume in a series is complete in itself, although it is not unusual for one to mention in passing, exploits from previous books. These books usually have fairly uniform appearance –– similar height, thickness, color, etc. Series books for children were published in this century by a great number of publishers. Saalfield, Whitman, Golden Press, Goldsmith, World, Clover, Doubleday, Garden City, Books, Inc. –– the list goes on and on. This brief explanation will revolve around Grosset & Dunlap, the publisher of the most famous and successful hard backed series books for children and young adults.

       Grosset & Dunlap publishers in New York originally published a great many adult fiction books (in addition to its children's series), near the turn of the century and into the 1930s. After the 30s they seem to have cut back on adult fiction and turned more toward books geared toward children and young adults. They did, however, continue to publish a good number reprints of some adult fiction such as books by Lloyd C. Douglas, Harold Bell Wright, and others.