In this paper, we propose proportional degradation services for multiple classes of adaptive multimedia services in wireless/mobile networks. First, we introduce two novel quality of service (QoS) parameters for the bandwidth degradation: the degradation ratio (DR) and the degradation degree (DD). Then, we propose two measurement-based call admission control (CAC) schemes to satisfy QoS requirements, and to utilize the resource efficiently. They are the window averaging (WA) scheme and the leaky-bucket integration (LBI) scheme. Finally, a K-level proportional bandwidth adaptation algorithm is also proposed to fairly adapt calls' bandwidth, to minimize DR and DD, to minimize DD with higher priority than to minimize DR, and to guarantee the ratios of service degradation among classes. © 2001 IEEE.