This book is based on a symposium to celebrate Eric Yu, the inventor of the i* framework, held on the occasion of his retirement and collocated with the 31st IEEE International Requirements Engineering Conference. The notion of social modeling emerged in the mid-nineties as a powerful conceptual approach to intricately analyze and specify complex social ecosystems, wherein strategic actors collaborate and depend on each other in order to attain their goals. The i* framework was designed precisely for this purpose, rapidly establishing itself as the de facto standard in the requirements engineering and information systems communities. The invited chapters, which were all written by highly acclaimed researchers, aim to give testimony to the impact of Eric’s work during the last 30 years of research and practice in requirements engineering (RE) and at the same time reflect on current development as well as future prospects. The content of the book is structured into five sections, relative to the relationship of each chapter to the i* requirements modelling language. The first four sections cover retrospectives and reflections on i*, empirical research studies on i*, i* modelling language variants, and applications of i* to address open research challenges. The last section presents a chapter – written by Eric Yu himself – on a vision how i* could foster the transition towards a new RE paradigm, i.e., RE as Augmenting Aspiring Selves, a paradigm that should better fit with the needs of RE for AI-based systems. This compiled collection of retrospective, ongoing and forward-looking scholarly essays centered on the i* framework furnishes its readers with a holistic vision of social modeling through i*, encompassing its versatile applications across different domains, challenges, and scenarios.