Epilepsy is one of the most stigmatizing of neurological conditions. Understanding how epilepsy affects the lives of important historical figures illuminates the psychosocial burden of disease for modern-day patients. Pius IX, one of the most consequential Popes in Catholic history, was reported to have epilepsy. Thus, this study aimed to assess how epilepsy influenced Pope Pius IX's life and his papacy. Librarians from Mayo Clinic, Library of Congress, and Vatican Library were consulted to identify all sources pertaining to Pius IX's health history. Twenty-one sources were consulted, and we conclude that Pius IX had partial epilepsy, likely a temporal lobe focus with secondarily generalized seizures. A near-drowning event in his youth coupled with a preexisting central nervous system lesion (as evidenced by photos showing facial asymmetry) likely contributed to his epilepsy. Epilepsy played an important role in Pius IX's life because it led him to the Papacy. At least one doctrine (the immaculate conception of the Virgin Mary) was influenced by his seizures, but there is no direct evidence that epilepsy played any role in the creation of other Catholic dogma ratified during his reign. Analysis of bias in references showed that favorable views of the Pope tended to minimize any discussions of his epilepsy, whereas negative references discussed his epilepsy at length. Pius IX's life holds lessons for modern-day epilepsy advocacy.