Absorptive capacity is the limiting factor for utilizing the almost inexhaustible innovation potential of Open Innovation Communities. In four case studies, Ivo Blohm examines the selection of ideas from Open Innovation Communities in the context of the absorption processes and competencies of community operators. Through the case studies, the author demonstrates how community operators absorb ideas from Open Innovation Communities, what IT-based competencies need to be developed for this purpose, and how mechanisms for collective idea evaluation, which allow community users to assess ideas collaboratively, simplify the processes of idea selection and absorption. The design of such evaluation mechanisms is assessed in three experiments that compare the classification quality and acceptance of evaluation scales and information markets.