This collective paper, or, more properly, this collection of ideas upon different classes of books, requires a word of explanation. The contributors were not asked to prepare papers but to furnish ideas and opinions, which should form the basis for discussion of the general principles of selection and of individual books in the several classes considered. The purpose was to present briefly the principles that should apply in each class, and to emphasize these by citation of specific books. _I. FICTION._ We were recently asked to make out a list of a dozen books suitable as prizes for a Sunday-school class of boys and girls from 12 to 16 years of age. We studied a long and carefully prepared list of stories written for girls of this age and supposed to include what was most desirable. Assuming that the girls had read Mrs. Whitney and Miss Alcott, we did not consider them, and we found not one story which we could recommend as possessing permanent interest and literary value. There were many books which girls read and like but they did not reach a fair standard for this purpose. We filled out the desired number for the girls with books written for older readers. Far different was our experience with the books for the boys. It was only a matter of choice between a large number, both suitable and desirable, and yet the lists which we consulted had been compiled by the same hand. In making selections of books for her readers, the children's librarian encounters at the first step this difference in the quality of the books written for boys and those written for girls. Judged purely by the standard of taste, she must reject the greater proportion of those written for girls. When she finds so few that reach her standard she may blame herself for ignorance of the better books, but she must ultimately reach the conclusion that whatever her own shortcomings there is a lack of desirable books for girls. However, another most important factor comes into the case on the reader's side of the question. If the librarian is going to meet the needs of her readers she must understand what they are instinctively seeking in books, and she must enlist herself on the side of human nature. She will find at once that a distinct division in the reading of boys and girls springs from the fact that, generally speaking, the mental life of the boy is objective, that of the girl subjective. The boy seeks action in fiction, the girl is attracted by that which moves her emotionally or relates itself directly to her own consciousness, and the last thing that either of them cares about is the literary value of the book. Hundreds--no doubt thousands--of our college graduates look back to the period when, according to their sex, the "Oliver Optic" series, or the "Elsie Dinsmore" series, played a very important part in their existence. The love of adventure in the boy gave the charm to the books. Adventure he