The thesis presents three theories of generative grammar, namely the Standard Theory (ST), Government and Binding theory (GB) and Lexical-Functional Grammar (LFG) and explains how these handle non-finite (infinitival) predicates. All of the three theories deal with how sentences are generated in the English language but they have a different approach. Both ST and GB are connected to the name of Noam Chomsky who is considered to be the father of generative syntax. GB is the improved version of ST as the constantly emerging problems resulted in the creation of it. LFG was developed by Joan Bresnan and her followers parallel to GB. It is remarkable as it offers an approach that is absolutely divergent from the two previous ones.