Criteria for selecting the papersThe publication “Citizens as sensors: The world of volunteered geography” in November, 2007 can be considered as a mark of the formal arrival of crowd-sourcing in the discipline of GIScience. Hence, we take it as a cut-off time and consider papers published thereafter. In exceptional cases, we also include few other papers published prior to this particularly if they inspired the “Citizens as sensors” paper. Geography is a science of sciences as asserted by Dewey (1943): “the unity of all sciences is found in geography” (p-26). Dewey's assertion implies that mapping and geographic information underpin most other disciplines. We are aware that different aspects of crowd-sourced mapping are being explored in other disciplines, resulting publications into a wide range of outlets. However, we do not intend to review all those publications. Instead, we focus on the mainstream GIScience/Geography journals with an attempt to organize this growing body of work, trace emerging themes, and identity their implications to GIScience practice and scholarship. In this pursuit, we consider papers—both conceptual and empirical—from the following journals:i. International Journal of Geographic Information Scienceii. Annals of the Association of American Geographers iii. Environment and planningiv. GeoJournalv. Geomaticavi. The Professional Geographervii. International Journal of Spatial Data Infrastructure Researchviii. Transaction in GISix. Cartographicax. Which others?