This book introduces life history evolution to postgraduate students just beginning their research in population biology, ecology, or evolutionary biology. It discusses major analytical tools, gives examples of their applications, and provides problems for discussion at the end of each chapter. It will interest all biologists wishing to understand the evolution of the life cycle and the causes of phenotypic variation in fitness, and it contains the seeds of applications of life history theory to population dynamics, behaviour, and community ecology. Care is taken in Part I to build up the tools needed for a well-rounded evolutionary explanation: demography, quantitative genetics, reaction norms, trade offs and phylogenetic/comparative analysis. Part II discusses the evolution of major life history traits. This is a comprehensive, up-to-date text in a field that holds a central position in modern ecology and evolution.