This book presents the results of 15 years of input-output (I-O) research on schooling effectiveness. The I-O approach identifies and measures the inschool and out-of-school factors that contribute to schooling outcomes, especially reading skills and verbal and mathematics achievement. Five categories of inputs are reviewed in this textbook: (1) student characteristics, (2) family characteristics, (3) peer group (classmates or schoolmates) characteristics, (4) teacher characteristics, and (5) school characteristics. The publication attempts to examine all the important input-output studies done in the United States and to synthesize them into an extensive set of propositions about what makes a difference in education. Several chapters provide an introduction to statistical methods to enable a reader with no statistical training to review educational research more critically. Linear regression analysis is dealt with in detail. An appendix detailing important studies of schooling effectiveness is intended for researchers and advanced students. (Author/JM)