A distinction between plain and preglottalized initial voiced stops is reconstructible for all primary branches of the Kra-Dai phylum at three places of articulation. This distinction may be hypothesized to be a secondary development within Kra-Dai, where the diachronic trajectories of what were originally medial voiced stops depended on whether or not the preceding vowel was schwa. While this plain versus glottalized opposition in the voiced obstruent series is quite robust within Kra-Dai, the same is not true for the sonorants. However, the Kam-Sui branch of Kra-Dai is particularly conservative in this regard, and a four-way phonation opposition (preaspirated, voiceless, voiced, and preglottalized) can be reconstructed for all sonorants with the exception of the lateral. While it has generally been assumed that these phonation differences reflect the different glottal states of the initial consonants of sesquisyllabic words before the presyllable was lost, the suggestion is put forward here that the preglottalized series of sonorants is not the result of conditioning by the presyllable initial. Rather, on analogy with the voiced stops, it occurs in an environment following schwa in which gemination occurred, followed by debuccalization of the first half of the geminate.