The kindly reception accorded to the first edition of this book has confirmed the author in his conviction that such a book was needed, and has tempted him to bestow additional labor upon it. The chief changes consist in the addition of two new chapters, "Active Imagination," and "How to Develop Interest in a Subject"; the division into two parts of the unwieldy chapter on memory; the addition of readings and exercises at the end of each chapter; the preparation of an analytical table of contents; the correction of the bibliography to date; the addition of an index; and some recasting of phraseology in the interest of clearness and emphasis. The author gratefully acknowledges the constructive suggestions of reviewers and others who have used the book, and hopes that he has profited by them in this revision. Educational leaders are seeing with increasing clearness the necessity of teaching students not only the subject-matter of study but also methods of study. Teachers are beginning to see that students waste a vast amount of time and form many harmful habits because they do not know how to use their minds. The recognition of this condition is taking the form of the movement toward "supervised study," which attempts to acquaint the student with principles of economy and directness in using his mind. It is generally agreed that there are certain "tricks" which make for mental efficiency, consisting of methods of apperceiving facts, methods of review, devices for arranging work. Some are the fruits of psychological experimentation; others are derived from experience. Many of them can be imparted by instruction, and it is for the purpose of systematizing these and making them available for students that this book is prepared.