Mounting an effective international humanitarian response to a chemical, biological, radiological or nuclear (CBRN) event, especially if the response is undertaken on an ad hoc basis, would be extremely difficult and would pose many risks to the responders. The International Committee of the Red Cross (ICRC) has created a competency-based capacity to respond to at least small-scale CBRN events, including a deployable capability to undertake operational activities. This involves informed assessments of CBRN risks, timely and competent decisions on how to respond, and effectively mobilizing appropriate resources to implement these decisions, through the creation of an emergency roster. In addition to the acquisition of technical expertise and material resources, the creation of such capacity requires the application of central processes, ensuring systematic management of CBRN response (including risk-based decision-making), standing operational procedures, and availability of and access to the necessary resources. Implementation of the ICRC’s CBRN response framework as described in this article should be considered by any agency or other stakeholder preparing for international humanitarian assistance in CBRN events – especially if such events are related to armed conflict.