This concise and widely referenced monograph has served as a text for generations of advanced undergraduate math majors and graduate students. Prepared with an eye toward the needs of applied mathematicians, engineers, and physicists, the treatment is equally valuable as a reference for professionals. After discussing some mathematical preliminaries, author Raimond A. Struble presents detailed treatments of the existence and the uniqueness of a solution of the initial-value problem, properties of solutions, properties of linear systems, stability in nonlinear systems, and two-dimensional systems. Additional chapters examine perturbations of periodic solutions and a general asymptotic method. Numerous exercises appear throughout the book, along with examples that contribute additional material, illustrate theorems and concepts, and provide a link with more practical aspects of the theory.