Even if Java is widely used for agent development, some agent platforms employ ad-hoc programming languages, so the question that arises is: Is there a language that fits the model of an autonomous software agent better than Java? This paper deals with such an issue by deriving an abstract model for agents and proposing some parameters to evaluate programming languages for agent development. As a result, the paper introduces Erlang, a functional language that presents some interesting characteristics for the engineering of agent-based applications. An Erlang-based platform, called eXAT and developed by the authors, is then presented. Finally, a comparison with a Java-based approach explains why, in the authors? opinion, this language cannot be considered a good choice for the implementation of agent systems.