This dissertation presents a Minimalist Theory of Control. As for the distribution of PRO, it provides evidence that PRO appears in a configuration of regular Structural Case assignment. This suggests that the complementary distribution between PRO and lexical subjects is not related to Case. It also provides empirical evidence against the Movement analysis of Control, which subsumes Control under Raising, and is compatible with the theoretical view that Theta Roles are configurational, rather than Features. It also renders the so-called Null Case unnecessary. The interpretation of PRO is the result of the need of the Chain of PRO to collapse with the Chain of the antecedent in order to survive at LF. Specifically, PRO is a featureless element and it is not in the Numeration. However, the system resorts to the off-line insertion of PRO to the Derivation to satisfy Theta Theory. This is a Last Resort operation that only takes place when there is no other DP in the Numeration to satisfy the existing Theta Roles. Although it appears in a local relation to a Case assigning Probe [+T], the defective nature of PRO makes it unable to host a Case Value. By FI, the Chain of PRO collapses, in the sense of Martin (1996), with a local Chain. This derives the Control effect. The complementary distribution of NP-trace, PRO and lexical subjects correlates with the degree of defectiveness in the feature composition of T's in each instance. Raising T is Defective ([-T, -person]), Control T is Partial ([+T, -person]) and T in lexical subject licensing is Complete ([+T, +person]). Minimally, [+T] assigns Case to subjects (PRO/lexical). Complete Probes license lexical subjects, where [person] relates to the presence of C. The explanation of why lexical subjects and PRO are in complementary distribution is the following: by Minimality, Partial-T prevents the definition of a Binding Domain. Unlike PRO, lexical subjects need a Domain, and Partial-T does not provide one. Complete-T excludes PRO because Complete-T involves a CP Phase. In this context PRO lacks an antecedent with which to collapse and the Chain of PRO violates FI at LF.