This study explores the underlying mechanisms responsible for the perception of cadential closure in Mozart's keyboard sonatas. Previous investigations into the experience of closure have typically relied upon the use of abstract harmonic formulæ as stimuli. However, these formulæ often misrepresent the ways in which composers articulate phrase endings in tonal music. This study, on the contrary, examines a wide variety of cadential types typically found in the classical style, including evaded cadences, which have yet to be examined in an experimental setting. The present findings reveal that cadential categories play a pivotal role in the perception of closure, and for musicians especially, ratings of the cadential categories provide empirical support for a model of cadential strength proposed in music theory. A number of rhetorical features also affect participants' ratings of closure, such as formal context, the presence of a melodic dissonance at the cadential arrival, and the use of a trill within the penultimate dominant. Finally, the results indicate that expertise modulates attention, with musicians privileging bassline motion and nonmusicians attending primarily to the soprano voice.