These data represent the Biotic Component (BC) of the Coastal and Marine Ecological Classification Standard (CMECS) out to -200 m or state waters (PMEP’s boundary) of the West Coast of the contiguous United States. The BC is organized into a branched hierarchy of five nested levels: biotic setting, biotic class, biotic subclass, biotic group, and biotic community. Classes and subclasses of the BC are determined by the dominant biota (defined as the most abundant in terms of percent cover) of the substrate. This is a data compilation; we cross-walked attributes from 20 datasets into CMECS BC ecological units. These classifications were applied to Nearshore Zones currently part of the Pacific Marine and Estuarine Fish Habitat Partnership’s (PMEP) spatial data system, within the “West Coast USA Nearshore Zones” (PMEP) layer. For full documentation of CMECS, see https://coast.noaa.gov/data/digitalcoast/pdf/cmecs.pdf.