This study aims to explain how the use of word of mouth communication and the background of the use of word of mouth communication as a method of da’wah contact with Hizbut Tahrir Indonesia (HTI). This study used a qualitative approach with case study design. The results of the study show that the use of word of mouth communication as a method of da’wah contact with HTI is applied in two activities, namely as a method of delivering da’wah messages and as a method of cadre with a chain system to official members who are stratified based on the study book or HTI curriculum. The background to the use of the use of word of mouth communication as a method of da’wah contact is based on the effectiveness and efficiency factors and sociocultural factors. In the form of direct communication, closeness, warmth, direct psychological response, trust, sincerity, authenticity and so forth. So as to provide a syabab satisfaction effect which has an impact on the commitment to remain on the path of da’wah, which is fostering self with Islamic tsaqofah and doing da’wah with used word of mouth communication from the muslem community.