This study aimed at identifying the purposes of using assessment by English language teachers in Oman. Participants were 369 English language teachers randomly selected from all governorates in Oman. The teachers were categorized into two groups based on the assessment system. The first group consisted of teachers teaching grades 7 to 9 because the assessment system in these grades places more emphasis on formative assessment. The second group consisted of teachers teaching grades 10 and 11 because the assessment system in these grades places more emphasis on summative assessment. A questionnaire was developed and administered to all teachers regarding the purposes of using assessment. A factor analysis of the teachers' responses revealed two dimensions of the assessment purposes: Instructional-versus learning-oriented purposes. Instructional-oriented purposes were related to teachers' use of assessment for evaluating their teaching methods and managing student behavior. Learning-oriented purposes were related to teachers' use of assessment for motivating students to learn and assigning grades for students. There were significant differences on using assessment for instructional-vs-learning-oriented purposes favoring learning-oriented purposes. There were no significant grade level differences on using assessment for instructional-vs-learning-oriented purposes. These results lead to a conclusion that the assessment system might not have an impact on the purposes for which assessment is used by the teachers.