This paper describes service models for peer-to-peer services in a mobile environment. These days, mobile devices such as PDAs and mobile telephones have the power and the capability to support a variety of services independently. In the near future, peer-to-peer services, for mobile devices in a mobile environment, will be commonplace. However, the performance of these devices is not comparable to those of PCs. The CPU performance of mobile devices is ten times less than those of PCs. Likewise, the data storage capacity of mobile devices is quite limited. Thus, it is difficult for these devices to provide peer-to-peer services such as file sharing and the access of CPU power. Hence, we propose suitable peer-to-peer service models for mobile devices. We have performed a large-scale experiment, with six hundred participants. This paper also contains the results and discussions of this experiment.