An evaluation of the relative responsiveness and sensitivity of selected measures of biological effects to a range in contaminant concentrations was performed in the San Francisco Bay area in 1987. The evaluation was performed to provide information to be used in selecting biological measures for possible inclusion in the National Status and Trends (NS&T) Program of the National Oceanic and Atmospheric Administration (NOAA). The NS&T Program analyzes three media—sediments, bottomfish, and bivalves—routinely at sites nationwide. This evaluation included biological tests of two of those media: sediments and fish.