This document discusses crowdsourcing and citizen history projects in cultural heritage. It defines crowdsourcing as outsourcing functions to a large network of people through an open call. Cultural heritage crowdsourcing involves meaningful public tasks related to collections that provide inherent rewards. Citizen science involves public participation in data processing, analysis, and research design. Participatory project models range from contributory to collaborative to co-creative. Examples of citizen history projects discussed include FreeBMD, Old Weather, Operation War Diary, and Children of the Lodz Ghetto. The document examines competing models of citizen history and structural issues that can undermine such projects.