The unitary competence theory claims the existence of a general language proficiency that makes the global evaluation of language skills possible and accounts for the high correlations between language tests of whatever form and modality. This study aims to test the theory by investigating the correlation between reading and listening comprehension of students under different linguistic environments. The cloze method was used to measure the reading comprehension of students in a second and foreign language setting, as well as to predict the degree of development of these language skills. The study also investigated whether differences in exposure to English as a Second Language (ESL) and English as a Foreign Language (EFL) yield differences in the degree of development of the language skills, and prove which of the two kinds of exposures leads to greater or lesser skills differentiation. The low correlation between the test rests leads to a question of the unitary competence theory. The results suggest that the cloze system may be a predictor of the differentiated degree of language skills development. Of the two groups taken as samples, the performance of the ESL students in the tests reveal that there is greater tendency for the listening skills to be specialized more than reading comprehension, or vice versa, while exposure to EFL may lead to less differentiation. Contains 37 references. (Author/LB)