The effectiveness of Responsive Teaching (RT) Early Intervention Program which is one of the relationship-focused interventions (RFI) on five children diagnosed with autism spectrum disorder (ASD) and their mothers was studied. The study was conducted in "Mixed Research Design" in which both quantitative and qualitative data were collected. Quantitative data of the study were collected through single group pretest-posttest model and qualitative data were collected from field notes, diaries, video analyses and interviews. Findings gathered from pretest and posttest quantitative results revealed that the RT program was effective on interactive behaviors of five children with ASD and their mothers. Qualitative results supported the quantitative findings and revealed that mothers stated they became more sensitive and responsive to their children behaviors by using RT strategies.