The labor force is aging globally. It is projected that the number of older workers will increase in the workforce in the near future. At the same time, it is estimated that workplaces will grow more age-diverse, where younger and older workers will work side-by-side more often than they used to. These demographic shifts in the workforce necessitate a further understanding of the differences between the values, needs and motivation, and work outcomes of employees of different ages. To this end, few studies to date have investigated whether job-related resources are differentially useful for the work and non-work outcomes of younger and older workers. Guided by Conservation of Resources (COR) theory and two lifespan development theories (Selection-Optimization-Compensation, SOC; Socio-emotional Selectivity Theory, SST), this dissertation suggests that the utility of resources is age-dependent. Specifically, this dissertation includes three studies that expand our knowledge of age-based differences in the usefulness of job-specific, social, and personal resources, and how they relate to various job attitudes, different forms of job performance, and employee well-being. Study 1, which was published in the Journal of Vocational Behavior, examines the moderating role of age in the relationship between baseline resources (skill discretion, leader-member exchange, and procedural fairness) and perceived stress after one year in a sample of U.S. construction workers (N = 243). As hypothesized, the findings of this study showed that these autonomy and support resources were more important for older workers: When resources were high in the workplace, all employees reported lower levels of stress. However, when resources were low, older workers experienced greater stress compared to their younger colleagues. In Study 2, multi-source data from Turkish manufacturing employees (N = 156) are utilized to investigate the age-based differences in the link between social support resources (leader-member exchange, perceived organizational support) and supervisory ratings of in-role performance and organizational citizenship behaviors in a cultural context other than the U.S. It was hypothesized that these social support resources would be more important for older workers' performance. However, the findings showed that both leader-member exchange and perceived organizational support were considered as equally important by older and younger workers to perform well at work. Finally, Study 3 explores whether resource from job (decision-making autonomy) and personal resources (optimism, perceived work ability) differentially relate to work attitudes (job satisfaction, work engagement) and well-being (perceived stress, emotional exhaustion) of older and younger nurses (N = 111) working in the Pacific Northwest, U.S. The findings of this study supported that the usefulness of decision-making autonomy and optimism were more pronounced for older workers. Overall, the results suggested that, when these resources were low, all employees had lower job satisfaction and work engagement, and greater emotional exhaustion and perceived stress independent of their ages. However, under high resource conditions, older employees shined at work and in life: When resourceful, they enjoyed their job more and felt strong and vigorous at work, and they perceived an overall sense of control over life as well as had an ease of mind at and outside of their work environments. Taken together, the findings of these three studies suggest several implications for theory and practice, particularly those pertaining to the key role that age may play in understanding different workers' needs for job-related resources and how this may affect their work attitudes, behavior, and well-being. Theoretical implications suggest that COR theory can be integrated with lifespan development theories to address the age-related differences in the resource utility. In addition, the findings of this dissertation highlight the need to examine employee age as a main study variable to explore the boundary conditions of various resources -- work and non-work outcomes. Implications for practice include recommendations such as facilitating job crafting and job redesigns for older workers, developing managerial trainings on relationship building with subordinates, creating a fair work environment through transparent organizational policies and practices, and improving personal capacities through stress management interventions. Avenues for future research are discussed as well, including identifying additional resources (e.g., overqualification, support from coworkers and family), and work and well-being outcomes (e.g., objective health measures such as sleep, sick days, and injuries) that may show age-based differences based on lifespan development theories. Finally, this dissertation highlights the need to replicate these study findings across industries, job types, gender, and culture as the usefulness of resources may be context-specific.