Drawing on Conservation of Resources Theory and previous research on work engagement, the present study investigates gain spirals between employees' engagement and their task, social, and personal resources. It focuses on the key resources of job control, positive work relationships, and active coping behavior. In a three-wave design, work engagement (T2) is suggested to function both as an outcome and antecedent of these resources, so that engagement mediates indirect longitudinal effects of initial (T1) on subsequent (T3) resources. Item-level structural equation modeling supported our hypotheses in a three-wave panel (N = 416) of hospital physicians with measurement intervals of 14 and 19 months. Connections between engagement research and other evolving perspectives in organizational research are highlighted. Unique contributions of the present study and their implications for further research and practice are discussed.