"This book began as lecture notes developed in connection with a course of the same name given since 1968 at Indiana University. The audience can be loosely grouped as follows: junior and senior mathematics majors, many of whom contemplate graduate work in other fields; undergraduate and graduate students majoring in the social and life sciences and in business; and prospective secondary teachers of mathematics. In addition, portions of the material have been used in NSF institutes for mathematics teachers. The goal of the course has been to provide the student with an appreciation for, an understanding of, and a facility in the use of mathematics in other fields. The role of mathematical models in explaining and predicting phenomena arising in the real world is the central theme. "--Preface.