The present cross-lagged panel study aimed to investigate the energizing power of job resources and related gain spirals. Drawing on Hobfoll's Conservation of Resources (COR) theory's rarely tested assumptions of cumulative resource gains and gain spirals a reciprocal process was expected: (1) job resources lead to work engagement and work engagement leads to personal initiative (PI), which, in turn, has a positive impact on work-unit innovativeness, and (2) work-unit innovativeness leads to PI, which has a positive impact on work engagement, which finally predicts future job resources. The study was based on a two-wave 3-year panel design among 2555 Finnish dentists. Structural equation modeling was employed to study cross-lagged associations. The results mainly confirmed our hypotheses: positive and reciprocal cross-lagged associations were found between job resources and work engagement and between work engagement and PI. In addition, PI had a positive impact on work-unit innovativeness over time. (Contains 4 figures and 2 tables.)