Empirical support is provided for the hypothesis that benthic communities found in relatively constant and predictable environments are less stable (resistant and resilient) following unusual disturbances than lower-diversity communities found in more inconstant and unpredictable environments. A less diverse benthic community (i.e., the Streblospio-Tubificoides assemblage) inhabiting an inconstant and unpredictable, shallow marsh cove was disturbed less and recovered faster from an experimental addition of No. 2 fuel oil, than the more diverse benthos (i.e., the Nucula-Mediomastus assemblage) inhabiting a relatively more constant and predictable, deeper coastal embayment. Disturbed sediment had a stimulatory effect on most populations in the marsh and an inhibitory effect on most populations in the bay. Initial amount and subsequent behavior of oil were similar in the two environments. Thus, differential responses of the two communities are attributable to intrinsic biological properties rather than differences in levels or composition of oil.