Previous research on dispositional optimism has predominantly concentrated on the selection effect of dispositional optimism on predicting work outcomes. Recent research, however, has started to examine the socialization effect of life experiences on fostering dispositional optimism development. Extrapolating primarily from the TESSERA framework of personality development (Wrzus & Roberts, 2017) and the literature on dispositional optimism, the current study represents a first attempt to reconcile the 2 seemingly contrasting perspectives. We proposed and examined change-related reciprocal relationships between dispositional optimism and work experience variables including income, job insecurity, coworker support, and supervisor support. Latent change score modeling of data from a five-wave longitudinal study demonstrated that dispositional optimism resulted in decreases in job insecurity, and the decreased job insecurity in turn promoted further increases in dispositional optimism later on. Furthermore, income gave rise to increases in dispositional optimism at a later point in time, but not vice versa. No significant relationships were observed between dispositional optimism and coworker and supervisor support. The findings provide a cautionary note to the majority of previous research based on cross-sectional and lagged designs that assumes causal effects of dispositional optimism on work outcomes. They also showcase the importance of examining personality change in organizational research and enrich our understanding of a more nuanced dynamic interplay between the optimistic employee and the work environment. (PsycINFO Database Record (c) 2019 APA, all rights reserved).