This paper reports the findings of a study designed to investigate the types of supportive discourse moves employed by Persian speakers in their Requestive Speech Acts. 372 respondents took a Discourse Completion Test (DCT) with six scenarios ranging from formal to informal degrees of Perceived Situational Seriousness, and returned 2232 Requestive Speech Acts (RSAs). The acts were then analyzed according to models proposed by Færch and Kasper's (1989), Blum-Kulka, et al. (1989), and Scollon and Scollon (2001). Results, after analysis of the data, indicated that Persian speakers use external and internal discourse moves to negotiate face in RSAs. It was concluded that Perceived Situational Seriousness was the determining factor in the choice of the type and number of discourse moves in a given RSA.