Book excerpt: A definition of leadership that would be widely accepted by the majority of theorists and researchers might say that "leadership is a process of social influence in which one person is able to enlist the aid and support of others in the accomplishment of a common task." The major points of this definition are that leadership is a group activity, is based on social influence, and revolves around a common task. While this specification seems relatively simple, the reality of leadership is very complex. Intrapersonal factors (thoughts and emotions) interact with interpersonal processes (attraction, communication, and influence) to have effects on a dynamic external environment. Each of these aspects brings complexity to the leadership process. It is the purpose of this book to make that complexity a bit more manageable, increasing the ability to understand what effective leadership is. This volume offers a comprehensive analysis and integration of the empirical research literature and major theories of leadership. It employs a functional analysis stressing what leaders must do to be effective and specifies the processes related to each function. The chapters provide an extensive review of the major approaches to leadership. Each chapter is discussed with an eye to explaining the basic principles, the research evidence, and where appropriate, the relationship of the theory or research program to other theories. In addition, this volume offers the most comprehensive treatment of cultural and gender factors in leadership of any recent book. The question of male-female differences in leadership style and performance is carefully analyzed against the empirical findings. The ultimate goal of this review of the literature is to provide a basis for the presentation of an integrative model of leadership that brings together function and process and provides an armature for integrating what is known.