In European Seas, plastic litter from fishing activities, river transport, and poor waste management is one of the fastest growing threats to the health of the marine environment. Extruded polystyrene (XPS) and expanded polystyrene (EPS), specifically, have become some of the most prominent types of marine litter found around Europe's coastlines. To combat this problem, the European Commission has ratified a series of regulations and policies, including the Single-Use Plastics Directive and the EU Action Plan for the Circular Economy. However, in order to ensure that the benefits of such regulations and policies are realized at a scale that can adequately address the scope of the problem, decision-makers will need to integrate the opinions, values, and priorities of relevant stakeholders who operate across the EPS/XPS product lifecycle. In this study, we apply a 35-statement Q-methodology to identify the priorities of stakeholders as they relate to the Irish EPS/XPS market and the wider societal transition to a circular economy. Based on the responses of nineteen individuals representing industry, policy-makers, and community leaders, we identified three distinct perspectives: System Overhaul; Incremental Upgrade; and Market Innovation. The results demonstrate that the type and format of policy interventions linked to Ireland's EPS/XPS circular economy are heavily contested, which presents significant challenges for driving the debate forward. These results provide valuable information on viewpoints that can be used by different stakeholders at national and EU levels to address areas of conflict, ultimately fostering the development of more effective, broadly supported co-developed policies.