This book, derived from an innovative course of lectures, is a first introduction to the mathematical description of fields, flows and waves. It shows students, early in their studies, how many of the topics they have encountered are useful in constructing, analysing and interpreting phenomena in the real world. Designed for second-year undergraduate students in mathematics, mathematical physics, and engineering, it presumes only a limited familiarity with several variable calculus and vector fields. It develops the concepts of flux, conservation law and boundary value problem through simple examples of heat flow, electric potentials and gravitational fields. The ideas are developed through worked examples, and a range of exercises (with solutions) is provided to test understanding. Chapters 1-7 contain ample material for an introductory lecture course, while later chapters on waves in fluids, solids and electromagnetism, and on bio-mathematics, show how the extension of earlier ideas leads to the description and explanation of important topics in modern technology and science. Written for: Undergraduate students of mathematics Undergraduate students of mathematical physics and engineering sciences Lecturers Keywords: Applied mathematics continuum mechanics continuum models mathematical physics