The European hammock spider, Linyphia triangularis Clerck 1757 (Araneae: Linyphiidae), has recently become established in Maine, with very high densities occurring at some coastal locations, e.g. Acadia National Park. In these high-density areas, native sheet-web spiders, such as Neriene radiata (Walckenaer 1841) and Pityohyphantes costatus (Hentz 1850), now appear to be scarce. In its native range, L. triangularis aggressively invades the webs of both con- and hetero-specifics, taking over webs by driving off or preying upon the resident spider. If native sheet-web spider populations are indeed negatively effected by the presence of L. triangularis, it may be due to interference competition related to this aggressive behavior or food-based resource competition. We present some of our findings from field competition experiments and provide commentary on which mechanisms we believe are more likely operating in this invasion.