An underlying form like /maːli/ is problematic for a stress system requiring word-final, bimoraic trochees. The grammar must sacrifice word-finality or bimoraicity, [(máː)li] or [(máːli)] (tolerating HL#); place stress on the second half of the long vowel, [ma(áli)] (breaking); or shorten the vowel, [(máli)] (trochaic shortening). This article surveys the Central Pacific language family, which hosts the most famous cases of breaking (Tongan) and trochaic shortening (Fijian), and finds that while trochaic shortening is poorly attested, breaking and tolerance are common. There are three findings of theoretical interest. First, length alternations suggest it is difficult to learn contrastive information that is absent in the core member of the morphological paradigm. Second, lexicalization of whole words is a possible response to this difficulty. Third, there is divergence between a language’s root phonotactics and its alternations.