The Free Online Encyclopedia, as Wikipedia called, is a radical departure from traditional encyclopedias and traditional methods of knowledge creation. This chapter explores how a community of amateurs on Wikipedia has challenged our notions of expertise in the 21st century. It does so by first looking at the roots of Wikipedia in a phenomenon known as the “wisdom of the crowds” and in the open source software movement. The reliability of Wikipedia is examined as are the claims of major critics of the project. Throughout, epistemological questions raised by Wikipedia are addressed.