Within building design team, communication has increasingly become multifaceted. Yet, despite the fast increasing communication modes and the introduction of design tools, most projects are still delivered below expectations. This study investigated the implication of design team’s communication on project success using a mixed research method (Quantitative and Qualitative approaches). Eighteen completed projects were randomly selected from five public organizations in Ibadan, Nigeria. Participants were drawn from the design professionals and client representative involved in each of the project (N=102). The quantitative data collected were analyzed using descriptive statistics and Pearson correlation coefficient analysis while qualitative data from semi-structured interviews were subjected to content analysis. Adequate participation of team members in meetings, provision of adequate information and appropriate use of design tools emerged as the key communication qualities which affect the project success. Based on these findings, recommendations were made towards improving design team effectiveness.