Achievement motivation is a consistent striving force of an individual to achieve success to a certain standard of excellence in competing situation. In this study an attempt was made to study the effect of achievement motivation on the academic achievement of the high school students of tribal and non tribal communities in relation to their sex and locale. For this purpose a sample of 200 students, studying in class IX of ten government high schools of Goalpara District of Assam was selected. They were administered the measures of Achievement Motivation Scale by Gopal Rao. "t" test and co-efficient of correlation (r) was applied to study the significance of difference between means and significant relation between achievement motivation academic achievement respectively. It was found that there was no significant difference between tribal-non tribal and boy-girl students but urban students have shown high achievement motivation than the rural students. In case of relationship between achievement motivation and academic achievement it was observed that there was no significant relation between achievement motivation and academic achievement of tribal, boy and rural students but there was a significant relationship between the achievement motivation and academic achievement of non tribal, girl and urban students. A bibliography is provided.