The theory and practice of Wikipedia has a common heritage with professional history. In spite of the project being very new, the number and variety of its authors and the ambivalence of academia towards it, Wikipedians have created an encyclopedia that upholds high standards of scholarship and encyclopedism. Simultaneously it provides universal easy access to knowledge. The policies and practices enacted by Wikipedia to achieve these standards are rarely unique. Facing the same challenges that encyclopedists, lexicographers, translators, librarians and archivists have before, it does not achieve a uniformly high standard but it is a new chapter in a very old book. This paper uses Wikipedia's articles to highlight practical means by which historians might engage with the project as a historical source and still maintain professional standards. Discussion pages, several associated paratexts and the statistics demonstrating article popularity are considered. Finally, there is a discussion about how historians can be directly involved in the Wikipedia project -- by editing it.