This document presents the findings of a study into methods that can help counterterrorism professionals make decisions about ethical problems. The study was commissioned by the Research and Documentation Centre of the Dutch Ministry of Security and Justice, on behalf of the National Coordinator for Counterterrorism and Security. The research team at RAND Europe was complemented by applied ethics expert Anke van Gorp from the Research Centre for Social Innovation at Hogeschool Utrecht. The study provides an inventory of methods to support ethical decision-making in counterterrorism, drawing on the experience of other public sectors – healthcare, social work, policing and intelligence – and multiple countries, primarily the Netherlands and the United Kingdom.