Abstract
Citizen science is one of the most dramatic developments in science communication in the last generation. But analyses of citizen science, of what it means for science and especially for science communication, have just begun to appear. Articles in this first of two special issues of JCOM address three intertwined concerns in this emerging field: The motivation of citizen science participants, the relationship of citizen science with education, and the implications of participation for creation of democratic engagement in science-linked issues. Ultimately these articles contribute to answering the core question: What does citizen science mean?