The development and deployment of robust and highly populated Wireless Sensor Networks require addressing a wide variety of challenges. Among them, the synchronization and energy management of the nodes composing the network have been identified as two challenges to overcome. In this paper, we follow a cross-layer approach by defining a synchronous engine built across the radio, MAC and routing layers. The design of our proposal has been based on the results of our previous research efforts dealing with various experimental platforms and experimental trials. © 2007 International Federation for Information Processing.