The relation of Mycobacterium avium ss paratuberculosis (MAP) to Crohn’s Disease (CD) and other MAP-associated conditions remains controversial. New data, coupled with the analogous Helicobacter pylori (H. pylori) story, has permitted us to piece together the MAP puzzle and move forward with a more scientific way of treating inflammatory bowel disease, particularly CD. As infection moves centre stage in inflammatory bowel disease, the dated “aberrant reaction” etiology has lost scientific credibility. Now, our growing understanding of MAP-associated diseases demands review and articulation. We focus here on (1) the concept of MAP-associated diseases; (2) causality, Johne Disease, the “aberrant reaction” hypothesis; and (3) responses to published misconceptions questioning MAP as a pathogen in CD.