We propose a model that explains the negative relationship between materialism and life satisfaction. We test negative affect as a mediator of the relationship between materialism and dissatisfaction with life, and gratitude and positive affect as moderators of this effect. Self-report data collected from 246 (129 female) undergraduate students generally supported our predictions. The negative relationship between materialism and life satisfaction was mediated in part by an increase in negative affect. Additionally, gratitude – and to a lesser extent, positive affect – functioned as moderators of the effect of materialism on life satisfaction. Individuals high in gratitude showed less of a relationship between materialism and negative affect. Additionally, individuals high in materialism showed decreased life satisfaction when either gratitude or positive affect was low. Thus, negative affect, positive affect, and gratitude seem to be important variables in the relationship between materialism and dissatisfaction with life.