The aim of this study was to investigating the effectiveness of communication skills training on self-differentiation among referring couples coming to registered offices in Masjed Soleiman city to get married. In this study, four couples (eight men and women) were selected using voluntary-purposive sampling method. The research design was single-case experimental of multiple baseline type. In ten sessions, couples were trained communication skills, and completed the Self-differentiation Questionnaire after training stages. The data were analysed by visual drawing method, Reliable Change Index (RCI), and recovery rate formula. The findings showed that communication skills training led to increase of self-differentiation (26.43%) in general, 27.37% in the first, 20% in second, 28.18% in third, and 30.23% in fourth couples. These were maintained percentages in follow-up stage. The Reliable change indices showed a meaningful change and increases in self-differentiation in during training and follow-up stages. The training led to relative increasing of couple's differentiation, and separated feeling of logic.
