This dissertation study attempts to understand excessive buying, a phenomenon of both theoretical and practical interest. I define excessive buying as "an individual type of buying behavior whereby consumers repetitively spend more than they should based on financial considerations". I develop a conceptual typology of excessive buying, building on the time-inconsistent preferences and automaticity theory. The new typology categorizes five specific types of excessive buying behavior: 1) habitual, 2) possessive, 3) remedial, 4) rewarding, and 5) out-of-control. Based on past literature and the typology, I generate scale items to capture the conceptual and logical variance in excessive buying. Psychometric properties of the scale are tested via Confirmatory Factor Analysis using a student and random adult sample. Nomological validity of the scale is confirmed by testing hypotheses formulated based on hedonic shopping values and the self-defeating behavior theory. The empirical analyses suggest that excessive buying results from stress, using shopping as an escape from reality, and little consideration for the potential outcomes of one's current behavior. Excessive buying leas to both financial problems and negative emotions.