Nominalization refers both to the process by which complex nouns are created and to the complex nouns that are derived by that process. Nominalizations common in the languages of the world include event/result nouns, personal or participant nouns (agent, patient, location, etc.), as well as collectives and abstracts. It is common for nominalizations to be highly polysemous. Theoretical issues concerning nominalization typically stem from the question of how to account for this pervasive polysemy. Within generative grammar, both syntactic and lexicalist approaches have been proposed. The issue of polysemy in nominalization has also been of interest within cognitive and functional frameworks. The article considers, finally, the extent to which nominalization is subject to competition and blocking.