Are higher levels of work-family enrichment a consequence or manifestation of certain personality traits and individuals' psychological functioning? Using random intercept cross-lagged panel models, this study examined the hypothesized stability of work-to-family enrichment (WFE) and family-to-work enrichment (FWE) over two 10-year intervals, the extent to which the within-person changes of WFE and FWE are associated with personality traits and psychological well-being (PWB), and possible gender differences. In this 20-year, longitudinal data analysis of employed adults (N=535), results indicated the robust nature of the stability of WFE/FWE. Our results suggest that personality traits were not associated with within-person change for either WFE or FWE, but PWB was associated with within-person change. Theoretically and conceptually, our findings provide strong evidence that work-family enrichment is not simply an "optimistic worldview" created by personality and well-being. The within-person results lend strong evidence that interventions that improve psychological well-being will also enhance work-family enrichment.