This article aims to present semi-structured interviewing as a pivotal tool used in research on the expressions of informal civil society, including the narratives of activists outside the third sector, but involved in grassroots initiatives. As quantitative research mostly focuses on formally registered organisations, it tends to legitimise and reproduce a narrow understanding of civil society. Semi-structured interviewing, on the other hand, is effective for gaining insight into hidden aspects of social life, problems that are not immediately perceptible. It enables the analysis of under-researched informal civil society and allows researchers to investigate the organisational challenges, practices and languages of unregistered initiatives. Nevertheless, research challenges include the ethical dilemmas related to power dynamics in research-participant relations, the positionality of the researcher and limited generalisability of the findings. Based on a literature review, including articles on civil society studies from five journals, I claim that interviewing opens the way to a more radical and broad understanding of civil society, which includes unregistered initiatives.