This completely updated textbook offers a comprehensive introduction to the subject of competencies from a scientific and educational policy point of view. The term "competency" is discussed from all possible aspects and is distinguished from the terms education, qualification and human resources. The author Dieter Gnahs shows how competencies develop and how they are fostered in educational practice. He introduces the latest most significant methods for recording and measuring competencies and explains who can apply them and how evaluations of competencies can be used. The final chapter looks at open questions in competency research, offers tips for further studies and gives an outlook on future developments.