Bioaccumulation factors (BAFs) and biota–sediment accumulation factors (BSAFs) are frequently used to predict contaminant bioaccumulation in risk assessments. Development of these parameters is often hindered by uncertainty regarding the spatial scale of contaminant transfer from sediments to biota. We present a simple statistical method for optimizing bioaccumulation parameters (BAF and BSAF) in aquatic species, such as fish, whose exposure history may occur over broad spatial scales. For 6 finfish species sampled in San Francisco Bay, San Diego Bay, or the Southern California Bight, California, USA, the spatial scale of correlation was optimized using regression analysis. The ranges identified for pairing biota and sediment observations generally corresponded to the known life histories of the species and with laboratory tests comparing relationships observed for 28-d Macoma spp. This procedure may be useful for identifying appropriate species and spatial scales to predict bioaccumulation and for developing data sets of corresponding sediment and tissue residues.