My dissertation examined the comparability of the test scores between the Indigenous and Non-Indigenous students, and the existence of a cultural bias present in the test items of the English Test of the Comprehensible Assessment Program for Junior High School Students. The statistical analyses of the test scores from the sample revealed the following information: The compositions of the measured constructs are dissimilar for the two groups; the reliability estimates of the scores revealed a 15% higher measurement accuracy for the Non-Indigenous students than for Indigenous students; the test items were ordered differently in terms of their difficulty level, but were ordered similarly in terms of their degree of discrimination; the test provided more information of students with different ability levels in the case of Non-Indigenous students than in the case of Indigenous students. My study did not find any evidence that would point to an existing cultural bias in the test questions. Taking everything into account, the results, limited to the non-representative sample of the students who participated in my study, indicated a low degree of comparability between the Indigenous and Non-Indigenous students’ test scores of the English Test of the Comprehensible Assessment Program for Junior High School Students. The results did not prove the existence of cultural bias in the context of the questions.