Drawing upon the thriving at work and agism literature, we added unexplored thriving antecedents (i.e., negative age-based metastereotypes and associated reactions) to the thriving nomological network. Additionally, we investigated the thriving-turnover intentions link throughout the lifespan. Parallel multiple mediator models were used to analyze the role played by threat and challenge in the relationship between negative age-based metastereotypes and overall thriving. Survey results (n = 326 employees) showed that threat and challenge mediated this relationship, yet differential relationships between antecedents and thriving appeared when analyzing thriving dimensions (i.e., learning and vitality) separately. Relatedly, turnover intentions were negatively predicted by overall thriving, but learning and vitality effects on turnover intentions were distinct across age groups. Findings recommend a clearer distinction between thriving dimensions role in the thriving experience throughout the lifespan. Overall, this study contends that the combination of thriving and agism literature contributes to further understand employee growth.