"Wh"-words have been analysed as existential quantifiers (Chierchia in Logic in grammar: polarity, free choice, and intervention. Oxford University Press, Oxford, 2013; Fox, in Sauerland U, Stateva P (eds) Presupposition and implicature in compositional semantics (Palgrave studies in pragmatics, language and cognition). Palgrave MacMillan, Houndmills, pp 71-120, 2007; Liao in Alternative and exhaustification: non-interrogative uses of Chinese wh-words. Harvard University, 2010) or universal quantifiers (Nishigauchi, in: Theoretical and applied linguistics at Kobe Shoin 2, Kobe Shoin Institute for Linguistic Sciences, 1999). These two accounts have distinct predictions on how children initially interpret "wh"-words. The universal account predicts that children should initially interpret "wh"-words as universal quantifiers, whereas the existential account anticipates that children should start out with the existential interpretation. To adjudicate between the two accounts, the present study was designed to explore pre-schoolers' semantic knowledge of "wh"-quantification. Specifically, it investigated the interpretation of the "wh"-word "shenme" 'what' with 4-and 5-year-old Mandarin-speaking children and a control group of adults. Using a Truth Value Judgment Task (Crain and Thornton in Investigations in universal grammar: a guide to experiments on the acquisition of syntax and semantics. MIT Press, Cambridge, 1998), Experiment 1 evaluated whether children interpret the "wh"-word "shenme" 'what' as closer in meaning to the polarity sensitive item "renhe" 'any' or the universal quantifier "suoyou" 'all' in the antecedent of "ruguo" 'if' conditionals. Using a Question-Answer Task, Experiments 2 & 3 respectively investigated whether children interpret "shenme" 'what' as closer in meaning to "renhe" 'any' or "suoyou" 'all' in two types of questions: yes-no questions with the particle "ma" and A-not-A questions. It was found that both children and adults interpret "shenme" 'what' as closer in meaning to "renhe" 'any' than "suoyou" 'all'. The findings suggest that Mandarin-speaking pre-schoolers already have adult-like semantic knowledge of "wh"-quantification: wh-words are existential quantifiers rather than universal quantifiers. Due to the paucity of primary linguistic input, children's early mastery of the non-interrogative wh-words appear to support the biolinguistic approach to language acquisition (Chomsky in Aspects of the theory of syntax. MIT Press, Cambridge, 1965; Pinker in Language learnability and language development. Harvard University Press, Cambridge, 1984; Crain et al. in Language acquisition from a biolinguistic perspective. Neurosci Biobehav Rev, 2016. https://bibliotheek.ehb.be:2102/10.1016/j.neubiorev.2016.09.004).