This document summarizes the NTNU@MediaEval 2011 Social Event Detection (SED) task. It describes the proposed framework which includes query expansion, search, categorization, clustering, and refinement. It outlines two challenges involving detecting music venues in Rome and Barcelona, and events at venues in Barcelona. It discusses experiments comparing runs with different refinement and categorization approaches. Results showed tag metadata and entity names improved performance, and refinement improved completeness. Future work includes better use of entity names for refinement and general event clustering.