Job satisfaction's position within the nomological network and the mechanism outlined by theories of social exchange suggest that job satisfaction functions as a mediator of the relationship between various antecedent variables and volitional workplace behaviours. We extend social exchange theory to include perceptions of the total job situation and develop a model that positions job satisfaction as a mediator of the relationships between various internal and external antecedent variables, and three volitional workplace behaviours: citizenship behaviours, counterproductive workplace behaviours, and job withdrawal. The fit of a fully mediated model is good and all four classes of antecedents (dispositions, workplace events, job characteristics, job opportunities) contributed uniquely to the prediction of satisfaction. Job satisfaction is also shown to mediate most antecedent-consequence relationships, although two important exceptions are evident. A direct link from pro-social disposition to OCBs, and a direct link and one from anti-social disposition to counterproductivity, suggest that job satisfaction does not fully moderate the relationships between dispositions and contextual behaviours.