Children's librarians, traditionally and actually, have always felt that an essential part of their work is to broaden a child's interests in reading and to deepen his appreciation of quality in books. In other words, it is not enough to give a child the book he wants. He must also be unobtrusively persuaded to want the best books we have. There is another realization which, taken in conjunction with the one just mentioned, reveals the first pattern to be discerned in the building of a book collection for children. This is the recognition of the fact that generation after generation of children respond to the same books, and that, as the years pass, the ephemeral, the insufficiently worth-while, the expedient book is winnowed.