The process of constructing a scale of Prosocial Behavior for adults is presented. Reliability and dimensionality tests were conducted from the Classical Test Theory perspective. 90 items were assessed by means of the expect judge method; the items shortlisted were administered to reduced groups. 576 students of Psychology of the University of Buenos Aires, took part in the test. The internal consistency analysis shows a satisfactory ratio (alpha=.85; glb=.93), while the dimensionality analysis presents a four-factor structure. These factors were Empathic Behavior, Altruism, Help and Share. Numerous behaviors connected with emotional reinforcement and support posted a high average, while the items typically associated with philanthropist behavior, such as volunteer work, clothes/food/money donations, and with highly ultraistic practices yielded low scores.