The salt—marsh vegetation of Newport Bay was separated into littoral and maritime zones and was sampled quantitatively for frequency of occurrence and cover. The littoral zone (marsh proper) was divided into a narrow lower belt covered by Spartina foliosa, a broadest middle band dominated by Batis maritima and Salicornia virginica, and a narrowest upper strip influenced by Salicornia virginica and Monanthochloe littoralis. The maritime zone consisted of a bluff community composed of Suaeda californica and Salicornia subterminalis, or a dune associate pioneered by Oenothera cheiranthifolia and Heterotheca grandiflora. Nine species, principally Gramineae and Chenopodiaceae, dominated the marsh. Salicornia virginica accounted for the highest total average frequency and cover. Additional important species were Suaeda californica, Batis maritima, and Spartina foliosa. The plant community was extremely simple in the lowest areas (four species) and graded to a more complex, yet relatively simple plant community in the highest regions of the marsh (15 species). Correspondingly, the lower zones had sparse vegetational cover and the higher zones supported heavier growth, both in size and numbers of individuals. Although the marsh was subjectively divided into zones, individual species could not be readily segregated into zones since the frequency of each species varied along environmental gradients to produce a vegetational continum.