The Guidance Battery is visualized as an approximately six-hour instrument providing scores on, perhaps, 8-15 relatively independent factors, suitable for administration at two levels: 7-9th grade and 11-13th grade. These will be referred to as the High-School Battery and the College Battery, respectively. The high-school battery would be intended to secure aptitude and other measurements important to students and counselors in deciding between college preparatory, vocational, technical, commercial, or other senior high schools. Depending on the nature of validation it could also be used for occupational counselling. The college battery would be intended to secure aptitude and other measurements important in selecting major course work in college. For both levels the approach would be that of comparative prediction: the prediction of level of success in different areas arrived at by combining general prediction and differential prediction in such a way that a subject's chances of success in various fields of his interest may be compared.