A mobile ad hoc network consists of a set of portable computational devices, equipped with a wireless communication interface, that are randomly and dynamically distributed in space, and where each host serves as a router for the other hosts by discovering and maintaining multi-hop routes among the hosts. In general, protocols for mobile ad hoc networks are more complex than equivalent protocols for static networks, due to several properties of such networks, such as its dynamic topology, the mutual interference, concurrent access and smaller communication bandwidth of the wireless links, as well as, operation with restricted amount of energy, and scarce resources of the mobile devices. A main focus of research in mobile ad hoc networks has been the development, analysis and comparison of routing protocols for such networks. Therefore, there is some demand for environments that facilitate the rapid prototyping, the simulation and the debugging of protocols at the network and other layers for such networks. These environments should preferably be flexible, easy to use, and allow for the definition of different levels of abstractions for modeling the main characteristics of the mobile network, such as the pattern of mobility, the wireless links, the energy consumption, etc. This thesis describes the design and implementation of a framework for the simulation of mobile ad hoc networks, which aims at supporting the development of concrete simulation environments for prototyping, testing and doing the complexity and performance analysis of protocols for such networks.