For the most part, my study is a descriptive analysis of infinitival complement clauses and the corresponding subjunctive clauses in Romanian, that is, obligatory control (OC) structures. OC is a relation of obligatory coreferentiality between a matrix argument (controller) and the null subject of the subordinate (controlee) of the same sentence. An OC sentence constructed with infinitive is given in (1) and its corresponding subjunctive sentence appears in (2). (1) Radu a incercat (de) [a deveni doctor]. Radu has tried Comp Inf become doctor "Radu tried to become a doctor." (2) Radu a incercat (ca) [sa devina doctor]. Radu has tried Comp Sbj become.3sg doctor "Radu tried to become a doctor." Between the sixteenth century and roughly the middle of the twentieth century, OC structures were available in both variants (with infinitive and subjunctive) but infinitival complements were on the brink of disappearance, thus diachronic analysis is necessary. The two types of complements are analyzed in parallel and their components, the elements of control, are described in order to designate their syntactic status. It will be found that the infinitival particle de is a complementizer (C element) and the particle a is the infinitival mood marker (I element). The subjunctive particle sa is also an I element. The null subject (controlee) in these OC structures combines the characteristics of PRO in the classical approach of control, thus I assign this status to it. In addition, the history of the infinitive, besides its documentation value, provides valuable information on the status of the infinitival particles a and de at different stages of development. Finally, a theoretical framework is to be found to reflect the infinitival and subjunctive OC structures. The two (opposing) theoretical approaches of obligatory control considered are Movement Theory of Control (MTC) and Agreement Model of Obligatory Control. Due to case mismatch between the controller and PRO, and the presence of lexical complementizers, especially in infinitive clauses, the MTC is rather unattractive. The Agreement Model of OC seems to better reflect the Romanian OC-type constructions. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]