Word frequency is a critical factor in language processing and memory in a variety of dimensions, as demonstrated by extensive research in psycholinguistics. However, recent studies have indicated that contextual diversity, which counts the number of materials in which a word appears, can be a more reliable predictor of language processing than word frequency. The objective of this study was to examine whether the effect of contextual diversity and word frequency varies across language registers in the process of Korean visual word recognition. We calculated word frequency and contextual diversity measures from the written and spoken corpus of the National Institute of Korean Language and analyzed the lexical decision time data in the Korean Lexicon Project (KLP) using hierarchical regression. The results from both corpora commonly elicited a significant facilitatory effect of contextual diversity when word frequency was controlled with other lexical variables. The results of the analysis showed that contextual diversity has a facilitative effect on Korean word recognition when controlling word frequency and other lexical variables in both corpora. However, the effect of word frequency was not observed in the written corpus when contextual diversity was under control. On the othe...