Endocrine-disrupting pollutants in rivers and oceans represent a poorly understood but potentially serious threat to the integrity of aquatic and coastal ecosystems. We surveyed the hemolymph of lobsters from across southern New England and adjacent offshore areas for 3 endocrine-disrupting alkylphenols. We found all 3 compounds in hemolymph from every year and almost every region sampled. Prevalence of contamination varied significantly between regions, ranging from 45% of lobsters from southern Massachusetts to 17% of lobsters from central Long Island Sound. Mean contamination levels varied significantly as a function of region, year sampled, and collection trip, and were highest overall in lobsters from western Long Island Sound and lowest in lobsters from central Long Island Sound. Surprisingly, lobsters from offshore areas were not less contaminated than lobsters from inshore areas. Contamination levels also did not vary as a function of lobster size or shell disease signs. Contaminated lobsters held in the laboratory did not retain alkylphenols, suggesting that hemolymph contamination levels represent recent, rather than long-term, exposure. Our data set is the first, to our knowledge, to survey endocrine-disrupting contaminants in a population across such a broad temporal and spatial scale. We show that alkylphenol contamination is a persistent, widespread, but environmentally heterogeneous problem in lobster populations in southern New England and adjacent offshore areas. Our work raises serious questions about the prevalence and accumulation of these endocrine-disrupting pollutants in an important fishery species.