|Abstract:||In this article, we seek to demonstrate the descriptive and explanatory power of two central ideas in Optimality Theory: (i) the idea that there can be conflict among grammatical constraints; and (ii) that these conflicts are solved by the ranking of the constraints. We illustrate these points with an analysis of the sentence patterns in question-formation, as shown in Ackema & Neeleman (1998). However, our analysis is different from A&N (1998), as we propose functional constraints acting in the formation of interrogative sentence patterns. We actually propose three constraints: Economy, Morphological Marking and Focalization. As we understand, a grammar is a system of optimization in two senses: (i) its conditions are codifications of functional demands over the form of the sentences; and (ii) the interaction among these demands must include a way to solve eventual conflicts among them.