The major concern of this study was to examine relationships among students 'rnperceived academic competence, motivational orientations and academicrnachievement; investigate whether the variables jointly influence and predict academicrnachievement and to see grade and sex differences in students' perceived academicrncompetence, intrinsic, extrinsic and amotivation variables. A total of 750 participantsrn(398 males and 361 females) from grade 6, 8, and 10 were involved in the study. Arnquestionnaire was used to gather data about students' perceived academicrncompetence and motivational orientations. Students' first semester average academicrnscores (academic achievement) were collected from rosters of respective schoolsrnrecord offices. Correlation, multiple regression, and Two Way ANOVA were usedforrnanalysis. Results obtained through correlation displayed that perceived academicrncompetence significantly correlated with academic performance at the three gradernlevels. Self determined and motivational orientation also correlated significantly withrnacademic achievement at grade 10. Multiple regression analysis revealed thatrnperceived academic competence and amotivation had statistically direct effects inrnpredicting academic achievement respectively for the three grade levels. Extrinsicrnmotivation also had a direct negative predicting effect for grade 8 and 10 students.rnThe proportion of academic achievement variance accounted for by the independentrnvariables decreased as grade level increases. Analysis of ANOVA also indicated thatrnthe grade main effect found to be statistically significant for perceived academicrncompetence intrinsic, extrinsic and amotivation variables. The sex and grade-sexrninteraction were significant in perceived academic competence, intrinsic, extrinsicrnand academic achievement variables.rnFinally it was concluded that self determined students and students who have higherrnperception of academic competence would score higher in academic achievement.rnImplications are discussed and recommendations are also forwarded.