The scarce diffusion of Wireless Sensor Network systems is due to several factors, among them the complexity in designing, programming and testing applications for this technology. Too often too specialized solutions have been proposed for specific scenarios, impeding code reuse and supporting poorly engineered development methodologies (i.e. “code and fix”). In this work we claim that Erlang, a concurrency-oriented functional language, could greatly reduce the complexity of designing this kind of applications, while at the same favouring sound engineering practices and simplifying testing and simulation of applications. There are challenges in effectively using this language on WSN systems, but in our opinion the effort will be paid off.