Recent literature dealing with that t or Empty Category Principle (ECP) effects has been concerned mainly with their occurrence in embedded sentences. In this squib, I will argue that ECP effects can also be observed in English main clauses. More specifically, I will propose that the nonapplicability of Subject-Aux Inversion (SAl), an otherwise obligatory rule, in cases of subject extraction (for example, *who did t come) can be explained in terms of the ECP. (For discussion of the ECP, see Chomsky (1981).) I will then show how such an account, relying crucially on the assumption that SAl moves the Aux into Comp (den Besten 1978), sheds some light on a language like Dutch, in that it establishes a nontrivial correlation between systematic that t violations in embedded clauses and the obligatory application of Verb Second in main clauses. Finally, I will briefly discuss the implications of the analysis for the acquisition problem.