This introduction presents an overview of the key concepts discussed in the subsequent chapters of this book. The book presents an overview of the European Union (EU) policies and governance architecture for sustainable development, focusing in particular on its development and policy programmes developed within the framework of the so-called sustainable development mainstreaming approach. It provides a comparative analysis of the UK and Italian national strategies for sustainable development that paying particular attention to the degree of political commitment, ambition of goals and specific policy priorities and instruments identified at the national level. The book focuses on actions for sustainable urban development. It also focuses on analysing the implementation of the Covenant of Mayors. It analyses the Eco-Innovation programme. The book addresses a number of issues related to the design and implementation of its internal policies with the objective of appraising the EU capacity to guide policy changes towards sustainability, through the perspective of the following some dimensions.