Scheduling plays an important role in providing quality of service (QoS) support for multimedia networks. We propose a cross-layer scheduler at the medium access control (MAC) layer for multiple connections with diverse QoS requirements, where each connection employs adaptive modulation and coding (AMC) scheme at the physical (PHY) layer. Each connection is assigned a priority, which is updated dynamically based on its channel and service quality; and the connection with the highest priority is scheduled each time. Our scheduler provides diverse QoS guarantees, uses the wireless bandwidth efficiently and enjoys flexibility, scalability and low implementation complexity. The performance of our scheduler is evaluated via simulations in the IEEE 802.16 standard setting.