Mediation of peace agreements bringing an end to armed conflict has become increasingly popular since the end of the Cold War. In the context of armed conflict, mediation has been undertaken by states, non-governmental organisations, regional and international organisations, and even individuals. Until recently, international peace mediation was undertaken on an ad hoc basis and in the absence of formal guidelines. Recently, however, various attempts have been made to formalise and professionalise international peace mediation to a certain extent. The UN and EU have set up offices dedicated to mediation, non-governmental organisations have been branded as ‘mediation experts’ and have led and supported mediation processes in conflict zones and numerous sets of guidelines, seeking to guide and regulate mediators have been created. This paper analyses the theory and practice of international peace mediation, with a special focus on the codes of conduct which seek to direct these mediators.