Effective and efficient Quality of Service (QoS) management is critical for a service grid to meet the requirements of both grid users and service providers. We introduce Q-GSM, a scalable framework for service management in grid environments, to address this problem. Main characteristics of our framework are 1) grid level resource reservation mechanism; 2) mapping application level service quality to sufficient quantitative reserved resources through negotiating with resources reservation interface; and 3) contract-like service level agreement management of grid services.