Request performances can be influenced by contextual factors. This paper examines the explanations of the request formulations of six Vietnamese learners of English in Australia. The retrospective interviews provide interesting insights into learners' request wording, such as the underlying motivations and reasoning, that are not apparent in traditional analyses of the forms. First, an analysis of learners' contextual perceptions shows that age differences, perceptions of the relative role relationship, and the formality of the situation influence their request formulation. Second, learners' judgements of politeness and their reported use of politeness devices suggest that learners may rely on supportive moves to manage harmony with their interlocutors. Therefore, the study suggests that appeal to alternative sociopragmatic interpretations could be the main reason for the differences in making requests between Vietnamese learners of English and English native speakers. The findings may advocate the explicit teaching of request speech acts for Vietnamese learners.This study employed retrospective interviews following discourse completion tasks (DCTs) to explore learners' pragmatic knowledge about request speech acts. Requests are both common and sensitive in daily communication. They are particularly important for learners in a studyabroad context who cannot avoid making requests during their stay. Request formulations are influenced by contextual factors which are culture specific (Spencer-Oatey, 2008). To make an appropriate request for a specific communicative situation, a learner has to take into consideration the contextual factors involved, for example, the relative social power and the extent of social distance from the interlocutor, and then be able to select appropriate linguistic forms to carry out the act (Spencer-Oatey, 2008).Literature on requests has predominantly focused on performance data, such as role-plays or written DCTs. Little research has provided insights into what underlies request performances, especially for Southeast Asian learners of English. Examining transcriptions of verbal reports could be one useful method in interlanguage pragmatics (ILP) research, since this could provide insights into learners' perceptions of speech act situations and the influence of such perceptions on speech act utterances (Cohen, 2004). This study used interviews following written DCTs to examine the reasoning for request formulations by Vietnamese learners of English regarding perceptions about contextual factors, politeness consideration, and the use of supportive moves (i.e., peripheral elements).