The relationship between job satisfaction and life satisfaction has been heavily researched over the years. In spite of this research interest, results have not proved conclusive in demonstrating the causal nature of the relationship. In the present study, a causal model was hypothesized and tested that involved simultaneous consideration of cross-sectional and longitudinal effects between job and life satisfaction. This type of analysis has not previously been conducted and allows the strongest conclusions to date regarding the causality between these constructs. Results based on a national probability sample of workers indicated that job and life satisfaction were significantly and reciprocally related. The cross-sectional results suggested a relatively strong relationship between job and life satisfaction, but the longitudinal results suggested a weaker relationship over a 5-year period, particularly with respect to the effect of job satisfaction on life satisfaction. The meaning of these results in the context of past research on the job satisfaction–life satisfaction relationship is discussed.