In this paper we present a synchronization scheme for multiagent systems (MAS) that supports complex forms of agent interaction. Synchronization in a MAS is necessary whenever the agents of that MAS are able to act simultaneously and it is essential to treat these actions as if they happened together. We use the general model of a situated MAS where agents and objects have an explicit position in the environment. Existing synchronization schemes resolves the problem of simultaneity of action, but do not include communication in the model. The focus of this paper is on the complex problem connected with the synchronization of situated actions (i.e. actions performed by the agents of a situated MAS) in relation to messages. The synchronization scheme we present integrates communication with actions. The scheme enables functionality for the agents (1) to coordinate their synchronized actions, i.e. to communicate with one another in order to agree on a future cooperation and the point in time to act simultaneously, and (2) ensures that simultaneously performed actions are treated as such. Throughout the text we use a simple multi-agent application, i.e. the Packet{World, as a case to illustrate the topics discussed in the paper.