This course delves into the internal composition of words (morphology) across languages. What is a word? What can be inside of a word? Do all languages build words in the same way(s), with the same sorts of ingredients? How similar is word-building to sentence-building? We will engage deeply with both the empirical and theoretical side of this topic, exploring not just morphology, but also its interactions with phonology (sound systems) and syntax (sentence structure). This class will be highly interactive and hands-on, and students will develop tools of analysis and argumentation that are applicable in all areas of linguistics and beyond.