The scientific investigation of the relationship between resources and retirement well-being is impeded by the lack of proper measurement of resources. This study reports on the development of an inventory that assesses resources relevant to retirement well-being. The 35-item Retirement Resources Inventory (RRI) is a self-report measure consisting of three factors. The RRI was extensively evaluated in a sample of 267 Australian retirees aged 50. years or above. In general, the three subscales of the RRI were shown to possess good internal consistency (0.81-0.89) and test-retest reliability (0.83-0.88) within a one-month interval. Retirement resources, as assessed by the RRI, significantly accounted for additional variance in both retirement satisfaction (16%) and retirement adjustment (22%) above and beyond that explained by demographic variables. More importantly, results from cross-lagged panel analysis indicated that retirement resources predicted retirement well-being rather than the reverse. Findings from the current study provide strong support for the resource perspective, which proposes that resources are critical to well-being in retirement. Theoretical and practical implications of these findings for retirement planning and designing retirement interventions are discussed.