Abstract THE EFFECT OF TEACHING EFL ONLINE ON THE ACHIEVEMENT AND ATTITUDE OF GRADE 11 STUDENTS The present study investigates the effects of online English as a foreign language (EFL) course on students' language achievement and attitude toward learning. The study population consisted of grade eleven students taking the English Elective course in Omani government schools during the academic year 2006-2007. Two grade eleven English Elective classes of a total of sixty-four students from two different girls' schools in the Muscat region represented the sample of the study. Thirty-three students in one of the selected schools represented the experimental group, which received online instruction. The thirty-one students in the other school represented the control group, which received traditional classroom instruction. Two types of instruments were used to explore research questions. First, an achievement test was used to measure the students' language achievement following the completion of the elective course. Second, an attitude questionnaire was used to assess the students' attitudes toward learning EFL online The major findings of the study are as follows: • The results of the achievement tests revealed a significant difference between the learners' achievement of the experimental group and the learners' achievement of the control group using t- test that favored the experimental group who took the EFL course online. This finding indicates that the EFL online course was effective at improving learners' English language. Following the completion of the course, the results of the attitude questionnaire revealed that learners showed a positive attitude toward learning EFL online. In addition to other problems, technological breakdowns were the most common problem encountered by learners during the EFL online course. These findings lead to a number of recommendations for future EFL online courses offered by post basic schools as well as a recommended list of further studies in the area of online learning.