This study applies the semi-automated method of sentiment analysis to magazines and videos that have been produced by the self-proclaimed Islamic State (IS) in order to determine what thematic narratives are prevalent within this propaganda and how consistent these narratives are between the platforms of magazines and videos. The data for this study included 28 individual IS-produced magazines and 32 IS-produced videos. A sentiment analysis of this data reveals that while videos tend to utilize more negative language on average when compared to magazines, the ways in which specific words and topics are discussed and represented are largely consistent between the two media platforms. Additionally, the themes of Muslim persecution, religious piety, and vengeance against enemies that were partially identified through sentiment analysis were found to be in line with the themes that have been previously identified through other studies. This suggests that sentiment analysis can act as a valuable tool in the future study of extremist textual media more generally.