This article proposes an intervallic approach to classifying and interpreting sixteenth-century chromaticism. The approach is based on a distinction between active leading tones, which imply resolution by diatonic semitone, and stable notes, which do not. This distinction underlies a dyadic approach to categorizing contrapuntal uses of chromatic semitones, providing an alternative to prevalent classifications by interval of triadic root or bass motion. The article distinguishes three chromatic semitone types: (1) normative/expressive, (2) chromatically deflected leading tones, and (3) chromatically thwarted leading tones. For each type, the article discusses representative examples drawn from motets and madrigals by Orlando di Lasso, Giaches de Wert, Luca Marenzio, Luzzasco Luzzaschi, Alfonso Fontanelli, and Carlo Gesualdo, and considers how the chromatic semitones express the poetic texts.