The study aimed at measuring the effects of the cognitive style (field dependence/independence), achievement motivation and sex and their interactions on the academic achievement among eleventh grade students in Al Batinah (North) Region in Sultanate of Oman. The sample of the study consisted of 475 eleventh grade students (243 males students and 232 females The achievement motivation test, which was prepared by Mosa (1981) was used for measuring achievement motivation, and the Group Embedded Figures Test, which was prepared by Alsharkawi & Alshikh (1976) was used for measuring the cognitive style (field dependence/independence). Acceptable reliability coefficients were obtained for these two tests. To answer the questions of the study, means, standard deviations for academic achievement in relation to the three studied variables, and three-way ANOVA were used. The results indicated that there are statistically significant differences in academic achievement attributed to cognitive style in favor of field independent students." Regarding achievement motivation, the significant differences in academic achievement were in favor of arts students with high achievement motivation, whereas no such differences were observed among science students. The differences between the academic achievement of males and females were statistically significant in favor of females. Regarding the effects of the interactions between the independent variables of the study on academic achievement, the results of the three-way ANOVA revealed that there were no significant two-way interactions. Similarly, the three way interaction was not significant. The results were interpreted in the light of the theoretical frame and previous related studies. Also, a number of recommendations and suggestions have been reached.