Using a case study of the Ardoyne Commemoration Project (ACP), a community-based ‘truth-telling’ project in the North of Ireland, this article explores the role that action research can play in researching sensitive topics in violently divided societies. The article focuses on the ethics of carrying out research that could be potentially harmful for participants and researchers. The principles that underpinned the work of the ACP, including participation, local ownership and control, and the role of ‘insiders’ are critically examined. The article argues that in situations where political violence has occurred and marginalized groups have experienced social injustice, it is ethically impossible and morally reprehensible for social researchers to remain detached and silent. Action research methodologies are framed by a commitment to social justice, giving voice to those who are usually silenced, challenging structures of oppression and acting withordinary people to bring about social change –therefore they offer appropriate research models for engaging in community-based ‘truth-telling’ in post-conflict situations.