Modern linguistic theory posits the existence of universal constraints. But whether these constraints concern lan-guage structure, generally, or speech, specifically, is unknown. To address this question, here we ask whether the constraintsidentified in spoken languages transfer to sign languages. ANCHORING (McCarthy & Prince, 1993) is a putatively universalconstraint on reduplication. ANCHORING requires that the final element of a suffixed reduplicant match the final element ofthe base (e.g., pana ‘chase’––>panana, ‘run’ not panapa). Here, we examine whether ANCHORING is likewise operative in asigned language. In our experiments, native ASL signers rated novel reduplicated forms: either ones consistent or inconsistentwith ANCHORING (i.e., ABB vs. ABA, where A and B are syllables). Results showed that signers reliably favored ABB formsover ABA. These findings show for the first time that ANCHORING constrains a sign language. This conclusion is consistentwith the existence of amodal linguistic principles.