This paper investigates the relationships among consonants in reduplicative forms with inserted consonants. I argue that there is a general tendency for the inserted consonant to be non-identical to the other consonants in a reduplicated form. This tendency to avoid identity among segments in a morphological constituent is attested in the native speakers’ behavior regarding consonant insertion in reduplicated words. I present evidence that this co-occurrence restriction is not only more sensitive to place of articulation than to manner, but it is also sensitive to positional distance between the participating consonants, based on examination of the reduplication data. The inserted consonants in reduplicative forms are more likely to be distinct from the first consonant than from the second in the base. The observed tendency indicates that co-occurrence restrictions are applied in Korean just as in many other unrelated languages. The restrictions were found to be working in the general lexicon, as well as in the specific vocabulary of Korean. (KC University, Assistant Professor)