Computational phylogenetics is an umbrella term for fascinating methods and tools that can be put to great use toward evaluating phylogenetic hypotheses. As such they have been gaining currency among linguists of various theoretical stripes. Yet, these methods and their results are often not fully understood. Certain results are cited as “irrefutable” even when the corresponding empirical bases and methods can be shown to be flawed upon thorough examination. In this seminar we will explore the scope and limitations of computational phylogenetics methods in historical linguistics, especially in studies of Creole formation. The objective is to see how to improve these methods while gaining a deeper understanding of Creole formation and, more generally, language change in language-contact situations. We will start with some general background on my “Cartesian-Uniformitarian” approach to Creoles and with some fundamentals of computational phylogenetics. Then we’ll evaluate the applications of computational phylogenetics in Creole studies. Given linguists’ increasing use of both computational phylogenetics findings, it is important that such methods be critically reviewed before they can be constructively and reliably applied in the analysis of Creole formation and other diachronic phenomena. (Much of the contents in this course is based on my collaboration with Robert Berwick and Trevor Bass.)