Situation theorists such as Jon Barwise, John Etchemendy, and John Perry have advanced the hypothesis that linguistic and mental representations are ‘situated' in the sense that they are true or false only relative to partial situations. François Recanati has done an important task in reviving and in many respects deepening situation theory. In this chapter, I explore some aspects of Recanati's own account. I focus on situated mental representations, and stress the connection between them and ad hoc or temporary concepts.