This paper presents the results of an experimental study on gradient acceptability of English sentences with two negatives such as ‘John didn’t eat nothing’ and ‘nobody didn’t eat’. These sentences have two possible interpretations. In the Negative Concord interpretation, the two negatives contribute a single semantic negation (e.g. ‘John ate nothing’). In the Double Negation interpretation, each negative contributes a semantic negation, yielding a logical affirmative (e.g. ‘John ate something’). Negative Concord is heavily stigmatized in contemporary English. The results of this study show that despite their overall unacceptability, Negative Concord sentences with a negative object are significantly more acceptable than Negative Concord sentences with a negative subject. This subject-object asymmetry is not present in Double Negation sentences, which are equally unacceptable with negative subjects and negative objects. This paper discusses how these results support the hypothesis that Negative Concord constructions have the same underlying structure as Negative Polarity Item constructions (e.g. John didn’t eat anything), which also exhibit subject-object asymmetries in acceptability (cf. *Anybody didn’t eat.)