This study investigates how speakers of Mandarin interpret negative sentences with the conjunction ("he" 'and'). Our experiments test three predictions that follow from the proposal that the Mandarin conjunction is a positive polarity item (PPI) for both children and adults. On this account, the Mandarin conjunction should be interpreted as taking scope over negation in simple negative sentences, but the conjunction should be interpreted "in situ" when negation resides in a higher clause than the one with the conjunction and, also, when the conjunction is elided from a negated verb phrase (VP). Experiment 1 confirmed the first two predictions. Both child and adult participants interpreted conjunction as taking scope over local negation, yielding a 'neither' interpretation. In a second condition, both groups interpreted conjunction "in situ" when negation was positioned in a higher clause, resulting in a 'not both' interpretation. Experiment 2 confirmed the third prediction. Participants from both groups interpreted conjunction insitu when it was elided from a negated VP, again resulting in a 'not both' interpretation. This complex pattern of linguistic behavior is evidence that the Mandarin conjunction is a PPI, as predicted, for both children and adults. We discuss how to explain the observed difference between Mandarin and English, where child and adult speakers assign distinct interpretations to negated conjunctions.