Two of the most fundamental—and most vexing—questions in sermon studies are “What is a sermon?” and “How can I find the sermons I need?” Tools for answering the latter question go by many names, ranging from the common (“bibliography,” “database”) to the obscure (“nomenclator,” “repertorium”). This paper will begin with a historical survey of these terms, from roughly the 17th century to the present day; after that, I will discuss and evaluate some of the more beneficial electronic resources currently available to sermon scholars.