This study investigated the relationship between the introversion-extroversion tendenciesrnof first year students at Addis Ababa University and their proficiency in English as a ForeignrnLanguage (EFL). It was hypothesized that in an ESLIEFL situation, introverted students wouldrnattain higher English proficiency scores in reading, grammar and listening tests because of theirrntendencey to prefer reading to talking, rules to examples, working alone to with others, figuringrnthings to talking to others. In order to test the hypothesis that introverts are more proficient inrnEnglish reading, grammar and listening, students from a randomly selected classes in the SciencernFaculty and the College of Social Sciences completed a personality questionnaire (EPI) and 45rnsubjects from the Science Faculty and 49 from the College of Social Sciences took an Englishrnproficiency test that was designed and formatted on the basis of examination papers normallyrnprepared by the Department of Foreign Languages and Literature (DEFLL).rnThe hypothesis that introverts are more proficient in English reading, grammar andrnlistening tests was not supported. The average score comparison showed that extroverts (bothrnmales and females) scored higher than introverts. No significant age difference was observedrnbetween introverts and extroverts.rnAlthough the correlation coefficient value showed a significant inverse relationshiprnbetween introversion-extroversion and English proficiency test scores in grammar and listening,rnthe insignificant correlation coefficient values for the relationship between introversionextroversionrnand reading as well as the total English proficiency test score are taken as evidencesrnfor the absence of significant relationships. These findings are discussed with respect tornpsychological and cultural factors that are predominant in Ethiopian society.