Software testing outsourcing is becoming attractive among organisations that desire to gain high quality products within reasonable cost while allowing testing experts to assure its quality. Despite these promising advantages however, organisations have yet to learn the factors that contribute to such projects’ success. The necessary planning and actions could not thus be taken towards the effort. Consequently, software testing outsourcing projects still fail. This study aimed to address this concern by collating the factors from previous research. The investigation continued by confirming the factors besides discovering other relevant factors from software testing practitioners. This study adopted qualitative approach where it employed semi-structured interviews involving five practitioners, who represented both client and vendor. The data were analysed using content analysis. The results show that there are two aspects to be considered, namely Process and People. The former contains nine factors and the latter comprises four factors. Each factor has specific elements, which delineates the characteristics or roles that it owns. The findings provide practitioners with understanding of conducting software testing outsourcing projects effectively.