Abstract: Recent studies have defined and explained the concept of ecosystem engineers and their effects at the ecosystem level. Ecosystem engineers are organisms that modulate the supply of resources by creating, changing and maintaining the physical structure of the habitat. Since ecosystem engineers play such an important role in the structure and function of the ecosystem it seems likely that they effect things like food web dynamics, population and community composition, species-specific interactions and animal behavior. Earthworms are ecosystem engineers that modify nutrient cycling, mesofauna, vegetation, and soil layers. Since all organisms affect and are affected by their physical environment, anything that the earthworm does will affect the top soil organisms like salamanders. Because salamanders use earthworm burrows, earthworms act as ecosystem engineers by providing additional habitat for certain salamander species. To asses this statement two experiments were conducted in microcosms. The first experiment determined that there was no difference between adult and juvenile Plethodon cinereus, a terrestrial salamander, in their habitat preferences and that they preferred artificial burrows more than cover objects or earthworm burrows. The second experiment examined the intraspecific interactions between individuals of P. cinereus in the presence and absence of earthworm, Lumbricus terrestris. We found that there was no competition between adults and juveniles for any of the habitats, although both adults and juveniles were found under cover objects more often when earthworms were absent. In addition, individuals in all treatments were often found sharing the cover object if earthworm burrows were absent. Field data supported experimental data in that a greater number of worms implied less use of cover objects and that there was no difference between adults and juveniles. By providing underground habitat for a common terrestrial amphibian, earthworms may have a fairly large impact on above ground faunal communities in the Northeast.