A study was conducted at the International University of Japan to see if second language (L2) working capacity correlates with L2 reading ability in advanced English-as-a-Second-Language (ESL) learners. The study consisted of a set of memory tests (Simple Digit, Simple Word, and Complex Span Test) and a set of measures of reading skills given to 32 students, with similar educational backgrounds, who were attending the university. Analyses of the data acquired from the various tests suggested a correlation between L2 working memory capacity and reading ability. Additionally, it was found that the L2 Complex Word Span measure correlated with measures of L2 reading skills, particularly the Test of English as a Foreign Language reading score and, thus, can serve as a useful measure in L2 reading development. It was established that if the working memory construct is to be of explanatory value in L2 (or L1) research, it will be necessary to demonstrate a causal, non-circular relationship between working memory capacity and the development of reading skills. The ultimate usefulness of the construct will depend on the degree to which working memory capacity can be established independent of the level of proficiency. In order to address this issue, converging evidence from multiple measures of working memory capacity and reading skill are needed. Contains 21 references. (GLR)