This book has two aims to critically review the Myers-Briggs Type Indicator (MBTI) and to outline and discuss some of the MBTI's applications in counselling, education, management and training. I examine the main underlying ideas and some of the best research and I try to spell out how the MBTI and Myers' psychological type theory can be most useful. I wrote the book with several groups of people in mind: 30 people who know their MBTI results or their psychological type (in Myers' sense); psychology students and others studying personality as part of a course. The book offers a viewpoint on some of the basic issues in personality as well as concentrating on the MBTI; anyone puzzled by and interested in themselves and others. The MBTI is an unusually positive and constructive approach; students and practitioners looking for a worthwhile research project in applied personality theory; my colleagues, - counsellors, psychologists, teachers, health professionals and managers.