This study investigates properties of adjunct control with a particular focus on Turkish providing an analysis for different types of adjunct control structures such as temporal adjunct clauses and purpose clauses, which have been understudied in Turkish linguistics. In analyzing adjunct control structures, I use Agree-based Theory of Control (ATC) (Landau 2000 and 2004) as a theoretical basis. I introduce a new interarboreal operation that I call Interarboreal Agree which draws upon the intuitions of Nunes (1995) that syntactic relations can be established between two unconnected trees. This analysis refines ATC in that ATC in its current form fails to account for Obligatory Control reading in adjunct control structures. An important overarching theme of this dissertation is the role of Aspect in determining control properties of adjunct clauses. As an example, I account for the structures that I call SOC (Subject or Object Control) structures in Turkish temporal adjunct clauses by assuming that these clauses do not have an Aspect Phrase projection. I also argue that Case variation in languages that have morphologically-dependent secondary predicates, that is to say, secondary predicates that agree with the NP they predicate in Case, gender or number, can be explained by the presence or absence of an Aspect Phrase projection. Aspect properties of adjunct clauses come into play in purpose clauses as well. For instance, in English, control in purpose clauses exhibits optionality in terms of the choice of the controller, which is not the case in the Turkish counterpart of the same type of purpose clauses. I argue that this is due to the fact that English purpose clauses do not have an Aspect Phrase projection.