This open access book provides a comprehensive exploration of research infrastructures (RIs) for open social science research, drawing on the case study of the FOSSR project. It covers the theoretical foundations, policy contexts, and FAIR data principles, before diving into the FOSSR project's research areas, governance, and capacity building strategies. The final sections focus on computational social science, collaborative research models, and future challenges in open science. With its interdisciplinary perspective and actionable insights, this book serves as a useful resource for researchers, policymakers, and data scientists working in the realm of open social science.