Situation awareness is a critical prerequisite for providing proactive assistance in the context of Ubiquitous Computing. In this chapter we will focus on the detection of high-level team intentions. At first we introduce an exemplary scenario of a team meeting in a smart environment and outline relevant criteria for our approach. Then we give a short insight into the current state of the art, discussing related research projects while trying to find points of intersections for a more generic modeling approach. We reflect team behavior and individual problem solving strategies against the background of social and cognitive psychology and review sources of prior information like domain knowledge and common sense to outline a basic generic model structure. We will argue that especially probabilistic model based approaches are capable of efficiently and robustly inferring activities by making use of this knowledge. We will take a closer look at models which are able to represent human behavior at different levels of abstraction, accompanied by a short explanation of their reasoning mechanisms for inference and prediction. At last we take a look at the synthesis of such models using planning methods for behavior sequences.