A major source of disturbance in New England salt marshes is the local accumulation of wrack, composed primarily of Spartina alterniflora and Zostera marina , Mats of wrack accumulate throughout the marsh, killing or damaging the plants beneath them. This study examines the formation of disturbance patches, their distribution in the vegetation and their subsequent successional development. Experimental placement of mats of wrack reveals that the zones of the marsh differ little in their sensitivity to this form of disturbance. However, the dominant grass species differ in their response to disturbance. The overall vegetation of the marsh reflects the pattern of disturbance in space and time as well as the successional development which occurs within indivdual patches.