These results show that no other factor, from the factors taken into account in this study, other than that of the intervention of differentiated instruction could have contributed to the changes that occurred in students’ achievement. Furthermore, it is shown that within the experimental group, none of the group of students was favored or disadvantaged by differentiated instruction. On the contrary, the achievement levels among all groups of students (socioeconomic group, achievement group and groups characterized by other socioeconomic factors) were higher on both the comprehension and literacy tests.