This paper presents a semantic foundation of temporal conceptual models used to design temporal information systems. We consider a modeling language able to express both timestamping and evolution constraints. We conduct a deeper investigation on evolution constraints, eventually devising a modeltheoretic semantics for a full-fledged model with both timestamping and evolution constraints. The proposed formalization is meant both to clarify the meaning of the various temporal constructors appeared in the literature and to give a rigorous definition to notions like satisfiability, subsumption and logical implication. Furthermore, we also show how to express temporal constraints using a subset of first-order temporal logic, i.e., DLRUS, the description logic DLR extended with the temporal operators Since and Until. We show how DLRUS is able to capture the various modeling constraints in a succinct way and to perform automated reasoning on temporal conceptual models.