||Kim, Chonghyuck. (2018). Child negation in Korean. The Linguistic Association of Korea Journal, 26(2), 39-60. Korean children are known to optionally misplace the negative morpheme an when they form negative sentences. Instead of placing it immediately before a predicate, they sometimes put it in a position removed from the predicate. Hagstrom (2002) proposes that Korean childrens errors are not something new but just language-specific instantiations of the errors commonly made by child speakers of all languages in the Optional Infinitives (OI) stage. Following Wexler (1998), he argues that Korean child negation errors result from the conflict between three constraintsthe Unique Checking Constraint, Realize Tense, and Realize Agreement. An important prediction that follows from his theory is that a Korean child has a 33.3 percent chance of making an error whenever (s)he utters a negative sentence. In this article, I aim to test Hagstroms theory and prediction. To this aim, negative sentences have been elicited from three children and analyzed. The result is that while children make optional errors in certain types of sentences, they make consistent or no errors in other types of sentences. This suggests that Korean child negation errors are controlled by sentence types rather than probability as Hagstrom claims.