The Covid-19 pandemic has further exposed humanity's vulnerabilities, while accentuating pre-existing inequalities. However, it also highlighted its strengths, not just in terms of the vaccines created in record time (albeit terribly unevenly distributed), but also in terms of highlighting the importance of health systems. The SOLIVID initiative, made up of 34 research groups from Latin America and Europe, was created in April 2020 as a metadata system of international solidarity actions that emerged in the context of the pandemic. In this book, published in collaboration with the Autonomous University of Barcelona, 43 authors seek to study and disseminate these collective solidarity actions, providing elements of debate and resources for a panoramic analysis.