Situation theorists such as John Barwise, John Etchemendy, John Perry and François Recanati have put forward the hypothesis that linguistic representations are situated in the sense that they are true or false only relative to partial situations which are not explicitly represented as such. Following Recanati's lead, I explore this hypothesis with respect to mental representations. First, I introduce the notion of unarticulated constituent, due to John Perry. I suggest that the question of whether there really are such constituents should (...) divide in two issues, one concerning language and the other concerning thought. Then I formulate a dilemma that any friend of cognitive unarticulated constituents must face: alleged unarticulated constituents seem to be either articulated or non-constituents after all. The dilemma is strengthened by the fact that unarticulated constituents cannot be inferentially relevant. In §4, three constraints on entertaining situated representations are spelled out. First, although the situation within which one is immersed is not represented as such, there must be cognitive facts that make immersion possible, and explain why one is implicitly related to a particular situation as opposed to another. Second, the move from a given representation to one which articulates the situation requires the capacity to contrast the latter with others in the same range. Third, I suggest that conceptual representations differ from non-conceptual ones in the permanent possibility of detachment that they allow. I then illustrate how these constraints work in three sorts of cases. In the first, thoughts like It's raining and It's over are implicitly related to their situations via some practical capacity of keeping track of particular places or times. In the second sort of cases, the relevant situations are not given, but stipulated, like in In Constance, it's raining. Cases of the third sort are those in which an unarticulated constituent is relevant to a whole system of representations, for instance the perceptual system. In the last section, I use the notion of ad hoc representation to defend the cognitive application of situation semantics against an important objection. (shrink)