Although theorized and generally accepted, research on the relationship (specifically the direction of the causal relationship) between person-job fit and work engagement is limited and not yet clear. Theoretical arguments can be presented for both directions, but empirical evidence is scarce. The study reported here explored the bidirectional relationship between person-job fit and work engagement in a longitudinal design. A three-wave cross-lagged panel design was used in a sample of 382 participants from the financial, healthcare, and manufacturing industries in South Africa. The results of Bayesian informative hypothesis testing showed the most support for the hypothesis stating that work engagement is a stronger predictor of person-job fit over time. Conversely, the hypothesis that person-job fit is the predictor of work engagement over time received limited support.