The concept of "Communities of Practice" has attracted attention as a way to support individuals' career development in today's society, where the job market has become increasingly uncertain. This book introduces the "Social Interaction Model for Youth Career Development," which is based on the concept of communities of practice. The model is specifically designed to assist young people overcome the challenges they face in their career development. In addition, it is applicable to a wide range of readers, as it is based on research conducted in both Denmark and Japan. The primary goal of this book is to serve as a valuable resource for young people as well as career guidance practitioners who are dedicated to supporting them.