Based on the EU Commission’s Fit for 55 proposals published in July 2021, this Final Study, commissioned by the European Parliament, discusses the challenges and impacts resulting from the integration of the maritime sector into the EU ETS, and the more stringent EU ETS for aviation. It considers implementation issues and the effect on the competitiveness of European stakeholders, such as those caused by carbon leakage, as well as the impact on sectoral employment. On the basis of the initial analysis and the results of stakeholder consultations, recommendations are provided on how to overcome implementation issues and adverse competitive and societal effects.