Second-language processing is unique in that virtually all aspects of its operation are crosslinguistic, involving two or more languages. The intent of this chapter is to explore the crosslinguistic nature of second-language processing, and in so doing, illuminate principled approaches to analyzing lexical competence among adult second-language learners. In this context, lexical competence refers to the range of capabilities directly contributing to the extraction of linguistic information coded in visual word displays. Previous research suggests that such capabilities evolve progressively through cumulative processing experience with target-language visual input (Perfetti et al., 1987). As a consequence, they vary systematically across languages in accordance with the manner in which lexical information is represented by graphic symbols in the writing system (Nagy & Anderson, 1999; Koda, 2002). Importantly, once developed in one language, these capabilities readily transfer to another language, and further mature through print processing experience in that language (Akamatsu, 1999; Koda, 1999, 2000). Thus, second-language lexical-competence development can be characterized as an amalgamated process emerging from crosslinguistic interactions between transferred first-language procedures and second-language visual input. Structural variations in first-language writing systems, presumably, are a major aspect of individual differences in lexical processing behaviors among second-language learners. Methodical investigations of such variance, consequently, should offer useful clues to understanding second-language lexical competence development. In this regard, it should be noted that the term “competence” is used inclusively in this chapter with reference to linguistic knowledge, processing skills, and cognitive abilities.