This chapter examines how the theoretical models of “reasonable expectations” developed in Part II apply within three distinct contexts of the EU’s General Data Protection Regulation GDPR: the “legitimate interests” clause (Art. 6(1)(f)), the provisions on further processing (Art. 6(4)), and the fairness principle (Art. 5(1)(a)). The analysis demonstrates that different aspects of the GDPR demand different interpretative approaches to reasonable expectations, reflecting the diverse objectives of each provision: For the “legitimate interests” clause, the chapter argues that the “normative model”, particularly its social norms-based variant, best serves the provision’s objectives. In contrast, regarding the provisions on further processing and fairness a transparency-based application of the cognitive model proves most persuasive. This chapter examines how the theoretical models of “reasonable expectations” developed in Part II apply within three distinct contexts of the EU’s General Data Protection Regulation (GDPR): the “legitimate interests” clause (Art. 6(1)(f)), the provisions on further processing (Art. 6(4)), and the fairness principle (Art. 5(1)(a)). The analysis demonstrates that different aspects of the GDPR demand different interpretative approaches to reasonable expectations, reflecting the diverse objectives of each provision. For the “legitimate interests” clause, the chapter argues that the normative model, particularly its social norms-based variant, best serves the provision’s balancing function. In contrast, for both the further processing provisions and the fairness principle, a modified cognitive model emphasizing transparency proves most effective. This varying application illustrates how theoretical models must be adapted to specific regulatory contexts while maintaining their conceptual integrity. The chapter concludes by offering practical guidelines for applying these different interpretative approaches within the GDPR’s framework, contributing to a more coherent and purposive application of “reasonable expectations” in EU data protection law.