<p>Fostering work ability, i.e., the ability to continue working in one’s job given prevailing demands, poses a significant challenge in today’s dynamic work landscape and aging society. Approach job crafting has emerged as an effective strategy to increase work-related resources, which are essential for meeting rising work demands. This study integrates Job Demands-Resources theory and developmental perspectives to investigate the relationship between job crafting and work ability across younger and older workers. Addressing previous shortcomings and ambiguities in the literature, it explores potential reciprocal effects between job crafting and work ability, determines their direction, and contributes to clarifying the role of age for job crafting prevalence and effectiveness. Using a random intercept cross-lagged panel approach, we analyzed data from 2769 German office workers surveyed four times over two years. Results revealed positive within-person cross-lagged effects of work organization, adoption, and metacognition on work ability across all participants, with no significant effects observed in the opposite direction. However, bidirectional within-person cross-lagged effects between metacognition and work ability were found for younger workers. While positive within-person cross-lagged effects of adoption on work ability also appeared only among younger workers, work organization showed positive effects in both age groups. In summary, this study proposes specific job crafting strategies as easily accessible approaches linked to improved work ability, while highlighting that their effectiveness may vary by age.</p>