A concise but rigorous textbook for advanced undergraduate and graduate students across the biological sciences that provides a foundation for understanding the methods used in quantitative biology. Biology has turned into a quantitative science. The core problems in the life sciences today involve complex systems that require mathematical expression, yet most biologists are untrained in this dimension of the discipline. Bridging that gap, this practical textbook equips students to integrate advanced mathematical concepts with their biological education. Mathematics in Biology covers three broad subjects--linear algebra, probability and statistics, and dynamical systems--each treated at three levels: basic principles, advanced topics, and applications. Motivations and examples are drawn from diverse areas of study, while end-of-chapter exercises encourage creative applications. Based on nearly two decades of teaching at Harvard and Caltech, this rigorous but concise text provides an essential foundation for understanding the methods used in quantitative biology. * Proven in the classroom * Suitable for advanced undergraduate and graduate students across the biological sciences * Offers accompanying online materials including code and solved exercises.