This study investigated the influence of the social interactional context on test performance from a sociocultural perspective. Two oral language test tasks were used and parallel task versions were developed using two test methods: the individual context and the group context. The tests were administered to 23 ESL students. Both quantitative and qualitative methods were employed to analyze the data. Results of this study, particularly the significantly different discourses generated from the individual context and the group context show that analysis of the influence of the social interactional context on test performance from a sociocultural perspective offers language test developers and researchers useful information about test development and test validation inquiry. Implications of applying sociocultural theory in second language oral performance assessment are discussed.