The central aim of this dissertation is to increase our understanding of changes in identifications and in the professional identity of employees, by investigating the prominent foci of identification, their mix in higher-order social identities and the personal and organisational factors (HRM and supervisory behaviour) that are involved in the change of these professional self definitions. Building upon the assumption that institutions for Higher Education and their workforce are being continually challenged to keep up and adapt to changing societal demands and that it is the quality and flexibility of the workforce which is the key factor to address this turmoil, this dissertation specifically focuses on the understanding of changes in teachers’ professional identity in higher vocational education. For this purpose four related empirical studies have been conducted. Together these studies illustrate the considerable professional diversity in the workforce and shed light on the relationships between foci of identification and professional identities, performance appraisal, leadership, career competencies, customization strategies, professional development and changes in teachers’ identifications over time.