In this book, originally published in 1987, John Ziman seeks the answers to crucial questions facing scientists who need to change the direction of their careers. A research scientist takes years to acquire specialized knowledge and skills. A whole career may then be spent as an expert in a very narrow field. But new discoveries and new social demands bring rapid change to science and technology. Is it really so difficult for scientists to move into new fields of research mid-career? How are their attitudes to change affected by their education, their research experience, their conditions of employment and their personal ambitions? How can they be helped through such periods and re-deployed for further useful scientific work? This book was written primarily for working scientists and their employers, in the language they would themselves use about their personal experiences and motives. For the non-scientist it provides many vivid glimpses of science as a career, and at the same time opens up a fresh area of the sociology of science, of social psychology and of management studies.