Generic sentences (e.g., “birds lay eggs”) express generaliza-tions about kinds, in contrast to non-generic sentences thatexpress facts about specific individuals or sets of individuals(e.g., “all birds lay eggs”). Although generics are pervasive innatural language, there is no unique linguistic marker of gener-icity, making the identification of generics a challenge. We in-vestigate the morphosyntactic cues that listeners use to identifywhether a sentence should receive a generic interpretation ornot. We find that two factors – the definiteness of a sentence’ssubject NP and the tense of the sentence – are extremely im-portant in guiding intuitions about whether a sentence shouldreceive a generic interpretation. We argue that the importanceof these factors can be explained by taking generic interpreta-tions to arise due to a failure to ground expressions as referringto specific entities or events.