The question of what it means for a document to be "effective" has significantly broadened from studying textual features in isolation to studying actual situations in which texts are produced and used. Usability testing looks forward toward meeting an up-coming communicative need, providing a way for writers with a document still under development to identify what aspects may cause problems for readers and assess whether the text is working well enough to satisfy readers' needs. While they are most often used for functional documents such as manuals, brochures, forms, and legal documents, the techniques of usability testing can also be applied to many forms of communication--and may be adapted for writing classrooms. The techniques of usability testing (including "thinking aloud") are illustrated with a case study of the usability of two versions of a form. Broader applications of the techniques of usability testing and thinking-aloud for exploring how readers respond to other kinds of discourse are explored.