© Oxford University Press 2011. All rights reserved. Project business is an emerging research field, which adopts a business-centric view to the management of projects, firms, and networks of projects and firms. Project business has been defined as "the part of business that relates directly or indirectly to projects, with the purpose of achieving the objectives of a firm or several firms". Relying on existing research, this article identifies firstly, the managerial challenges for successful management of projects and project-based firms and secondly, the research themes and opportunities that may enhance our understanding of project business. It uses the term "project-based firm" to refer both to firms that conduct part of their operations using projects and to firms that organize most of their internal and external activities in projects. Project -based firms and organizations are found in a wide range of industries, such as consulting and professional services, cultural industries, high technology, and complex products and systems.