The number of services that will become available in distributed networks (in particular, on the Internet) is expected to grow enormously. Besides classical services such as those offered by printers, scanners, fax machines, and so on, more and more services will be available nowadays. Examples are information access via the Internet, music on demand, Web services, and services that use computational infrastructure that has been deployed within the network. Moreover, the concept of service in mobile agent systems, which will be described in this article, has come into prominence recently. The mobile agent model is a new distributed software development paradigm as compared to the traditional client-server model. Instead of calling operations on servers with some form of synchronization, the user passes on his or her goal to an agent that can migrate within the computational environment and knows how to handle it without being controlled. In brief, mobile agents are active, autonomous, intelligent objects that are able to move between locations in a so-called agent system. Mobile agents must interact with their hosts in order to use their services or to negotiate services with other agents (Song & Li, 2004). Discovering services for mobile agents comes from two considerations. First, the agents possess local knowledge of the network and have a limited functionality, since only agents of limited size and complexity can migrate efficiently in a network and have little overhead. Hence, specific services are required that aim at deploying mobile agents efficiently in the system and the network.