As online consumer reviews have tremendously gained in importance for consumer decision-making and firm strategies, scholars have greatly advanced our understanding of the effect of various review characteristics on review helpfulness and product sales. However, the question of what actually caus-es variations in these review characteristics remains largely unexplored. This study addresses this gap and establishes a novel link between online reviews and reviewer personality by arguing that certain personality characteristics of reviewers play a crucial role in shaping the way reviews are composed. Specifically, we draw on an innovative and unobtrusive measure of personality in the context of online behavior by building on theory on political ideology. Numerous scholars have shown that individuals’ political ideologies are a result of stable, underlying personality characteristics. We hypothesize that, as a consequence, reviews by liberals exhibit more cognitively complex language, a greater diversity of arguments, more positively valenced language, a greater number of words, and a greater number of arguments compared to reviews by conservatives. By linking clickstream data to 245 online reviews, we provide support for our hypotheses. We discuss how the concept of political ideology can yield novel insights in online review research and how it allows website managers to provide more tailored incentives to potential reviewers.