Impulse buying by consumers has received considerable attention in consumer research. The phenomenon is interesting because it is not only prompted by a variety of internal psychological factors but also influenced by external, market-related stimuli. The meta-analysis reported in this article integrates findings from 231 samples and more than 75,000 consumers to extend understanding of the relationship between impulse buying and its determinants, associated with several internal and external factors. Traits (e.g., sensation-seeking, impulse buying tendency), motives (e.g., utilitarian, hedonic), consumer resources (e.g., time, money), and marketing stimuli emerge as key triggers of impulse buying. Consumers’ self-control and mood states mediate and explain the affective and cognitive psychological processes associated with impulse buying. By establishing these pathways and processes, this study helps clarify factors contributing to impulse buying and the role of factors in resisting such impulses. It also explains the inconsistent findings in prior research by highlighting the context-dependency of various determinants. Specifically, the results of a moderator analysis indicate that the impacts of many determinants depend on the consumption context (e.g., product’s identity expression, price level in the industry).