In the present study, we were interested in the appraisal by teachers who have had experience with an individual form of differentiation of the efficiency of grouping learners into homogenous or heterogeneous groups. In the study, seven aspects were thus considered: (1) the learning performance and motivation of learners, (2) the learners' activity, (3) didactic ways of adapting teaching to diverse learners, (4) the impact on the formation of learners' personality, (5) cooperation among learners, (6) opportunities for professional development, and (7) cooperation with parents. The research has shown that there is a statistically significant difference between the teachers who teach in homogeneous groups and the teachers who teach in heterogeneous groups in all the seven aspects of the appraisal of the efficiency of grouping learners into homogenous or heterogeneous groups. Regarding most of the assertions, teachers belonging to both groups perceive the way of teaching they perform as having the most advantages.