The document discusses open access publishing of monographs and describes the OAPEN project. OAPEN aims to develop an open access publication model for peer-reviewed academic books in the humanities and social sciences. It involves 7 university presses and 2 universities across 6 European countries. OAPEN is taking a hybrid approach, making the basic online edition freely available while other printed or e-book editions can be sold. Funding agencies would pay the costs of publishing the open access editions. The project has produced guidelines and tools to help implement this open access monograph model.