Introduction: For decades the Social Justice concept in education has been studied alongside and the possible implications of its use as a tool to promote more prosocial societies. Based on Nancy Fraser's multidimensional Social Justice Model, a program was designed to promote prosociality in 6th grade primary school students. The main objectives of this research were to become acquainted with the student's representations of Social Justice and to promote prosociality through a preliminary implementation of a designed educational program. Method: The methodology was based on eminently participative workshops inspired by cooperative learning. After an initial evaluation of the students' representations of Social Justice, a preliminary implementation of a socio-educational program was carried out with 84 students from various educational schools in Madrid (Spain). This program was structured in three main modules: 1) Discovering Social Justice; 2) Skills to discover and solve social injustices; and 3) Creating a common framework of Social Justice to coexist prosocially. At the end of the program, the changes in the Social Justice representations of the students were quantitatively evaluated. Results: The results showed improvements in the Social Justice representations that were evaluated at the beginning of the preliminary program, as well as in the ability to identify social injustices derived from the various trilemmas analyzed. Furthermore, significant improvements were evidenced in most of the trilemmas evaluated, showing that the students demonstrated a greater prosociality in their approach. Thus, the socio-educational program was effective regardless of gender and type of school to which the participating students belonged. Discussion and Conclusion: Based on this applied preliminary experience, the scope of the socio-educational methodology is discussed in order to promote prosociality through the principles based on Education for Social Justice. We concluded these kinds of programs are capable of promoting a more prosocial coexistence of the students inside and out of the classroom, promoting a greater understanding of the injustices lived by other people. Finally, some detected limitations and possible improvements for the definitive implementation of the program in the future are also discussed.