Four species assemblages of desmognathine salamanders are sympatric in and along many mountain streams of the southern Appalachians. The species, Leurognathus marmorata, Desmognathus quadramaculatus, D. monticola and D. ochrophaeus, span an aquatic to terrestrial habitat continuum ranging from totally aquatic (L. marmorata) to primarily terrestrial (D. ochrophaeus). Such a system afforded the opportunity of examining concepts of helminth parasite ecology within the context of several recent theoretical predictions. Parasite infracommuinities (populations of all helminth species within individual hosts) in salamanders are isolationist in character. That is, parasite prevalence (percentage of hosts infected with a given parasite species) and mean intensity (mean number of parasites of a given species within a species of host) are low, and as a consequence there is little potential for competitive interactions. Isolationist infracommunities in salamanders arise from factors including a simple enteric system, restricted vagility and ectothermic generalist insectivory. Salamanders have a broad prey base and they do not focus on any particular prey species. Transmission of helminths by intermediate hosts is unimportant and contributes to depauperate helminth faunas dominated by nematodes with direct life cycles. The least diverse infracommunities were associated with Leurognathus marmorata while Desmognathus quadramaculatus had the most diverse fauna. Patterns of prevalence and intensity of infection revealed that salamander helminths were, in general, not host specific. Rather, they are generalists and their distributions can be correlated with host size (age), diet and habitat preferences. INTRODUCTION A principal focus of community ecology is to interpret the effects of competition, predation, mutualism and parasitism, as well as abiotic factors, in determining community structure. Ecological theory has been largely derived from studies on free-living animals with little attention focused on specialist organisms such as parasites. Price (1980, 1984) emphasized that small, highly specialized organisms are very different in many aspects of their biology from larger, more generalized animals so that communities of specialists may be organized in fundamentally different ways from generalist communities. The current literature reveals a predominance of nonequilibrial communities in nature among specialists, in which biotic interactions play a minor role in maintaining community structure (Price, 1984). These are in marked contrast to the equilibrium communities, many of which conform to the predictions of classic competition-based theory (see Strong et al., 1984; Price et al., 1984, and references therein). As stated by Price (1984), "It is valuable to examine the extent to which specialist communities support or contradict the paradigms'" Despite their biological uniqueness and complexity, helminth parasites possess certain attributes which should permit them to contribute significantly to several basic concepts in community theory. First, helminth communities have unambiguous boundaries