This paper reports on the work of a European Commission DG Education and Culture co-financed project PBP-VC, Promoting Best Practice in Virtual Campuses, which is aimed at providing a deeper understanding of the key issues and critical success factors underlying the implementation of virtual campuses. The paper outlines a tentative model of issues underpinning best practice in virtual campuses derived from an initial literature-based investigation of existing virtual campus initiatives within the European Union. It is proposed that the tentative model will build upon key principles that have been identified for the development of an online constructivist learning environment based on problem-based learning and on a suitable model for knowledge construction and evolution. The tentative model comprises five main areas that can be viewed as being interrelated: (1) Organizational issues; (2) Technological issues; (3) Pedagogical Issues; (4) Financial Issues; and (5) Consolidation Issues. At a meta level the authors hypothesize the presence of the sustainability issue. The project is working towards developing a practical framework to help guide the process of creating best practice in virtual campuses, as well as raising awareness of issues and approaches to creating sustainable virtual campuses. In addition to the investigation of European Union virtual campus projects, the paper will consider virtual campus projects outside the European Union (e.g. North America, Asia, Africa) in order to identify best practices and explore the use of constructivist learning environments. The last phase of the PBP-VC project will be to conduct in depth face-to-face research with specific virtual campus projects and initiatives in order to learn more about the issues that underpin best practice, as well as sending out detailed questionnaires to virtual campus projects and initiatives throughout the European Union, as well as beyond. The detailed framework for best practices built upon the principles for the development of an online constructivist learning environment based on problem-based learning highlighted in this paper will be at last developed and refined. (Contains 2 figures, 2 tables, and 1 note.