This conceptual integration addresses how positive and negative mood states influence information processing in groups. In addition to the impact of mood on attention and arousal, the review develops the notion of dominant cognitive processing strategies that mediate the influence of positive and negative moods on information processing in groups. Positive moods are proposed to reinforce dominant cognitive processing strategies while negative moods inhibit or revise such dominant cognitive processing strategies. Principles derived from several mood-cognition models are applied to group information processes related to attention, encoding, storage, retrieval, processing objectives, response, and feedback. The impacts of mood states are discussed in relation to group themes of convergence-divergence, commonality-uniqueness, and accentuation-attenuation of cognitive processes. The analysis leads to new implications for small group topics such as metacognition, group learning, motivated information processing in groups, communication, mood dynamics, and mood composition. The principles described can inspire numerous directions for future research.