This study provides the first detailed account of perceptual dialectology within California (as well as one of the first accounts of perceptual dialectology within any single state). Quantitative analysis of a map-labeling task carried out in Southern California reveals that California's most salient linguistic boundary is between the northern and southern regions of the state. Whereas studies of the perceptual dialectology of the United States as a whole have focused almost exclusively on regional dialect differences, respondents associated particular regions of California less with distinctive dialects than with differences in language (English versus Spanish), slang use, and social groups. The diverse sociolinguistic situation of California is reflected in the emphasis both on highly salient social groups thought to be stereotypical of California by residents and nonresidents alike (e.g., surfers) and on groups that, though prominent in the cultural landscape of the state, remain largely unrecognized by outsiders (e.g., hicks).