There is widespread agreement within sustainability science that a radical sustainability transformation is needed to address the many crises ranging from climate change and biodiversity loss to growing inequality and poverty and the notion of transformative change is gaining momentum. The IPBES Global assessment defines transformative change as a fundamental change process in which technological, economic, and social issues are thought about and made radically differently than before. In this context, the debate is increasingly focusing on the responsibility of science and its role in promoting transformative change. Purely ‘top-down’ measures, or incremental steps are proving to be insufficient. Some are calling for a new cooperation between science and society, from which solutions can emerge ‘bottom-up’, allowing the Sustainable Development Goals and the Paris Agreement to be achieved. The main aim of this dissertation is to contribute to the advancement of transformative science - a new research paradigm, propagated since 2016 that is normatively oriented towards the provision and development of solutions for sustainable social change, and simultaneously pursues scientific, practical and educational objectives, with the explicit goal of transforming the science system. As such, the thesis focuses on methods of transformative science and contributes to a better understanding of how transformative science can be consistently underpinned by empirical methods. The dissertation proposes answers to the following questions: What makes a scientific method transformative or at least adequate for being employed in transformative science settings? What are appropriate criteria to measure their quality? How can empirical methods be designed or adapted for bottom-up transformative science? How can change agents be supported by transformative science? What added value is provided by a self-reflexive practice of transformative science scholars whose research is situated between science and practice? As its main contribution, the thesis develops an analytical framework for assessing the quality of transformative science methods, which encompasses the stated objectives in combination with basic normative assumptions and key characteristics of this research approach. Using the example of the “Human Scale Development approach” (HSDA) by the Chilean economist Manfred Max-Neef and his colleagues, which was initially designed and used as tool for Latin-American communities to take development issues into their own hands, the dissertation shows how an already existing method has been adapted for transformative science to generate action-oriented transformation knowledge in addition to analytical knowledge, while at the same time fulfilling the necessary quality criteria.Specifically, the thesis shows how the methodological and theoretical potential of the HSDA can be used to support ‘agents of change’ as drivers of sustainability transformation processes in the context of transformative science. By means of different case studies in energy initiatives in Chile and Germany, the dissertation outlines that considering the human dimensions and linking needs to sustainability opens up new perspectives on possible development paths. A case study of German renewable energy cooperatives is presented in detail to show how the HSDA could contribute to generating systems knowledge, target knowledge and transformation knowledge necessary for transformative change. The analysis of the HSDA serves as an example, indicating how other methods could be adapted for transformative knowledge co-production, and the proposed analytical framework could be used to check how they meet quality criteria.In a further step, the thesis changes perspective and turns to the role and the related necessary competencies of the researcher within transformative science. In turn, the HSDA is proposed as a tool for an autoethnographically sensitive, self-reflexive practice, which is acutely aware of the distribution of power and thereby takes a feminist stance. As a result of this reflection, the thesis identifies both endogenous and exogenous factors that are understood as indispensable for transformative science. The thesis concludes that in order to meaningfully implement transformative science, it is necessary to recognize new roles and competencies that go beyond the classic understanding of top-down science, as ‘acting objectively, generating descriptive-analytical knowledge’. Instead the additional aim of co-creating actionable knowledge is corroborated and the quality of its knowledge production processes can be meaningfully ensured by testing it with the criteria presented in the analytical framework.