|Abstract:||This paper explores the six ditonal sandhi that spawns from an inventory of four tones (Low, High, Rising and Falling) in an attempt to provide an account for why only these ditonal combinations trigger alternation but not others. Earlier accounts have relied on the OCP to apply to adjacent syllables both at the level of the full tone contour and also the tonal features that comprises the contour. Another account has been to explain sandhi in terms of leveling across syllables so that excessive contours are to be avoided. A careful exploration reveals that neither of these approaches are adequate, nor are some of their stipulations necessary. Instead, a more viable solution might be found if we accept that Tianjin prosody is right-headed such that the prosodic prominence is reflected through tone complexity. To this end, I propose the Head Tone Complexity (HTC) constraint that partners with OCP to generate the attested ditonal sandhi patterns.