Abstract: This paper explores the meaning of the word “felony” in thirteenth and fourteenth century England, i.e., during the first two centuries of the English criminal trial jury. To compile a working definition of felony, the paper presents examples of the language of felony drawn from literary and religious sources, in addition to considering the word’s more formulaic appearance in legal records. The paper then analyzes cases ending in acquittal or pardon, highlighting the factors that might take a criminal case out of the realm of felony. It suggests that the very definition of felony and felonious behavior—and thus the essence of criminal responsibility—may be bound up with the idea of mens rea during this period. The paper aims to uncover broader societal understandings of the nature of guilt and innocence, and to highlight connections and disconnections between the formal criminal law of felony, with its heavy emphasis on capital punishment, and popular and ecclesiastical understandings of culpability.