ABSTRACT Because online reviews facilitate consumers’ purchase decisions, prior research investigates factors impacting review helpfulness. By integrating Kuhlthau’s information search process model and the heuristic-systematic model, we propose that a situational factor – product quality uncertainty – shapes consumers’ information search processes and suggests which reviews are most helpful. The literature suggests that review length and information richness positively impact review helpfulness. However, their joint effect conditional on product quality uncertainty is unknown. An experiment reveals that consumers are motivated to process individual reviews only when uncertainty is high (i.e. when consumers disagree on product quality). Analysis of over 37,000 online reviews indicates that, under high uncertainty, short reviews with rich information are most helpful. Consistent with the experiment results, neither factor drives helpfulness when uncertainty is low (i.e. when previous consumers exhibit a consensus on product quality). We present managerial implications for stimulating “short and sweet” reviews to increase review helpfulness.