The iii (III) Chord

This AP Music Theory study guide covers the mediant chord (iii/III), its functions as tonic prolongation, weak predominant, and disguised dominant, and its role in tonic expansion (I-iii-IV-I). It reviews diatonic harmony and chord functions, explains the mediant's use in minor keys for tonicization and modulation, and provides practice questions on chord analysis and harmonic progressions. The guide also emphasizes contextual analysis and voice leading.