This research is an attempt to find out if grouping learners, through using a placement test will significantly help students become more successful in learning English. 320 non-English major undergraduates studying at the University of Isfahan participated in this research. The final scores of 121 freshmen who attended their general English courses in homogenised classes were compared with those of 199 freshmen who did not undergo any placement procedure. The analysis of data suggested that grouping the learners and dividing them into different ability groups had a significant impact on the participants' academic success, in their course of general English. In addition, the results suggested that ability grouping provides sufficient ground for methodological decisions and hence sequencing of teaching materials and procedures.