In this paper, I present a model of community assembly in the salamander genus Desmognathus based on a survey of assemblage composition throughout the range of the genus. The 21 species of Desmognathus can be sorted into three life-history categories, namely, stream, streamside, and forest, based on duration of the larval phase and a suite of other life-history and morphological traits that are correlated with habitat use of the several life-history stages. In most assemblages having all three life-history categories, stream species are larger than streamside species, and the latter species are larger than forest species. An evaluation of the literature on interspecific competition and predation (i.e., intraguild predation) in Desmognathus indicates that these processes are important in structuring assemblages of these salamanders. Thus, niche assembly, as opposed to dispersal assembly (i.e., neutral model), seems to be a valid model of community assembly in Desmognathus. Only streamside species occur throughout the range of the genus, and these forms alone are found around the periphery of the range. One to three streamside species form the base of extant assemblages of Desmognathus, with stream and forest species contributing to the more diverse assemblages of the southern Appalachian region. The maximum numbers are two or three streamside species, two or three stream species, and two forest species, although assemblages of more than six species are undocumented. I suggest that the rapid evolutionary diversification in body size and life history in Desmognathus that has generated the complex assemblages of this genus in the Appalachians has been facilitated by a high level of life-history symmetry in these salamanders.