Accepted Manuscript version of Frederick W. Dingledy, The Corpus Juris Civilis: A Guide to Its History and Use, 35 Legal Ref. Services Q. 231 (2016). The Corpus Juris Civilis is indispensable for Roman law research. It is a vital pillar of modern law in many European nations and influential in other countries. Scholars and lawyers still refer to it today. This valuable publication, however, may seem impenetrable at first, and references to it can be hard to decipher or detect. This guide provides a history of the Corpus Juris Civilis and the forms it has taken, states why it is still an important resource today, and offers some tips and tools for research using it.