The present study aimed at finding the possibledifference between the performance of two differentgroups of bilinguals (dominant bilinguals andbalanced bilinguals/biliterates) compared with regardto their performance on two sets of skills i.e. BICS(Basic Interpersonal Communicative Skill) andCALP(Cognitive Academic Language Proficiency). Thestudy also aimed at finding out the possibleinterdependence of these skills according to thetheory of Common Underlying Proficiency, proposed byCummins (1979). It was hypothesized that differenttypes of bilinguals perform the same on tests ofreading as a CALP skill and speaking as a BICS skill.A total number of 96 senior EFL students from theuniversities of Kurdistan, Iran, and Salahaddin,Iraq, were included in the study. Fifty two(28female, 24male) were biliterate Kurdish-Arabicstudents from Salahaddin University in Kurdistan,Iraq. The other 44 (12 female, 32 male) wereKurdish-Persian bilingual students of English fromKurdistan University in Kurdistan, Iran. The agerange of the subjects was 21-24. Language typology,age, language background, and gender were kept constant.