%X Environmental Policy Integration (EPI) is a policy measure that helps translating environmental interests into non-environmental policy sectors in order to facilitate sustainable development. However, the EPI processes are complicated as the economic interests often prevail in sectoral policy-making. Accordingly, the research focused on the role of informal institutions and barriers associated with EPI in Infrastructure sector policy-making in Lithuania. The study argues that informal institutions are highly relevant in order to facilitate environmental policy integration in sectoral policy-making since the professionalism culture in sectoral institutions resist change and provide with a number of barriers that restrict the EPI processes. Based on qualitative research methods and research conceptual model, the research suggests that informal institutions have a strong role in affecting the EPI processes, hence limiting the integration of environmental interests in infrastructure policy-making. In conclusion, the study suggest to focus on institutional capacity building to promote learning and innovation. %A Karolis Kincius %L theses_frw328 %D 2017 %T The barriers and role of informal institutions in environmental policy integration. Study case - Infrastructure sector, Lithuania.