Cobscook Bay, a boreal, macrotidal estuary in the northeastern Gulf of Maine is noted for its species richness and has been the site of extensive natural history investigations. In spite of this level of investigative activity, no quantitative survey of the subtidal, macroinvertebrate communities exist. Here we present the results of a 1975 benthic grab survey of outer Cobscook Bay prior to recent salmon aquaculture and port development. The limited 11-station survey resulted in the identification of 172 taxa. Densities ranged from 870 to 12,970 m⁻². Multivariate and qualitative analyses clearly dissected the station set into sandy cove stations and coarse sediment channel stations. Cove stations were characterized by burrowing and tube-dwelling infauna, while channel station fauna was epifaunal. Community distribution is controlled by strong tidal currents and resulting sharp geological discontinuities. Because 70% of the Bay bottom is floored by gravel, the epifaunal community characterizing the channel stations may be the most representative of the Bay. The grab sampler certainly underestimated large filter feeders that may be important in the nutrient budget of the Bay. Future surveys need to be more extensive and use a combination of sampling methods to quantitatively measure all components of the community.