The book deals with methods for solving ordinary nonstiff differential equations. This new edition contains in particular the following new material: Hamiltonian systems and symplectic Runge-Kutta methods, dense output for Runge-Kutta and extrapolation methods, a new Dormand & Prince method of order 8 with dense output, parallel Runge-Kutta methods, numerical tests for first- and second order systems. The reader will benefit from many illustrations, a historical and didactic approach, and computer programs which help him learn to solve all kinds of ordinary differential equations. This book will be immensely useful to graduate students and researchers in numerical analysis and scientific computing, and to scientists in the fields mentioned above.