Cooperation between the territories around the Irish Sea has a long history. Internationally, territorial cooperation arrangements come in numerous forms and are widely pursued as a means for territories to work together to address shared development opportunities and challenges. This report, commissioned by the Welsh Government, presents the findings of an initial scoping study on future territorial cooperation in the Irish Sea area. The report finds that cooperation between the territories around the Irish Sea has a long history and a role in the future and sets out guiding principles and proposes a new phase of territorial cooperation in the Irish Sea Area.