This book argues that the process of understanding must start from reflection upon one's own experience, and that the sort of wisdom devised entirely from the experience of others is, at best impoverished, and at worst illusory. This is particularly the case where one is concerned with the complex understanding of professional work involving the taking of decisions about and for other people, e.g. education, nursing, social work and management. The fundamental purpose of this book is to provide encouragement and advice for practitioners in such professions, about the process of action-research, as a method of professional learning.