This paper provides a short overview of some principles of the Minimalist Program, as originally outlined in Chomsky (1995). Within this framework, sentences are constructed in as economic a way as possible, e.g. movement is restricted. I formulate a few of these economy principles more precisely (the Head Preference Principle and the Late Merge Principle) and then go on to examine several cases of language change. Principles of economy fashion these changes, I argue. I will also study how language--external prescriptive rules and a typically human wish for linguistic innovation interact with the internal linguistic principles.