Book excerpt: The complex diffusion processes affecting the flow of planning ideas and practices across the globe are illustrated in this book. It raises questions about why and how some ideas and practices attract international attention, and about the invention processes which go on when external influences are woven together with local efforts to meet local specifics and requirements. Initiated to celebrate the tenth anniversary of the journal Planning Theory and Practice in 2009, this book reflects the themes of the journal. Taking different intellectual perspectives, this collection takes a critical look at the international diffusion of planning ideas and practices, their impacts on planning practices in different contexts, on the challenge of ‘situating’ planning practices, and on the ethical and methodological issues of international exchange in the planning field.