The formation of teacher identity is a complex and strenuous process. Teachers are expected to form multiple identities based on institutional values and regulations; however, these identities can sometimes conflict with one's personal values and goals, leading to less integration. According to self-determination theory, forming an integrated identity is crucial for teachers' well-being and effective performance. To promote an integrated identity, it is essential to satisfy the need for autonomy, defined in this study as the need to have a choice and the ability to self-determine one's behaviours. While much is known about the construction of social identity, the formation of an integrated identity is less understood. To fill this gap and support the professional development of early career academics (ECAs), this study adopts the concepts of organismic integration and basic psychological needs. It examines the extent to which ECAs' identity adoption is integrated (autonomous) or introjected (controlled) and the degree to which autonomy satisfaction is associated with adopting particular identities. A total of 176 ECAs teaching at various UK universities completed an online questionnaire based on the Basic Psychological Need Satisfaction and Frustration Scale; 25 of them also participated in a semi-structured interview. Generally high levels of autonomy satisfaction were determined, but the reasons given indicated the formation of externally regulated and introjected identities. Implications for developing effective professional preparation programmes are discussed.