This book presents a study of environmental policy integration (EPI) in the transport sector in Bulgaria. It is inspired by the challenge of pursuing sustainable development through formulating policies and instruments for long-term win-win solutions in the transportation and environmental sectors. EPI stands for the incorporation of environmental concerns into other sectoral policies at an early stage of decision-making improving policy coherence. Essentially, the book examines EPI as a process by analyzing factors such as a clearly defined sustainable development concept, political commitment, institutional set-up to steer integration, stakeholder involvement and knowledge management. Also, EPI is examined as a policy output entailing regulatory, market-based and information-based environmental policy instruments. The study provides new insights on some of the challenges for environmental integration in a country in transition and shall be particularly useful to practitioners and researchers working in the field of environmental mainstreaming in other public policy domains.