the speech act of disagreement has been one of the speech acts that has received the least attention in the field of pragmatics. this study investigates the ways power relations, social distance, formality of the context, gender, and language proficiency (for efl learners) influence disagreement and politeness strategies. the participants of the study were 200 male and female native persian speakers and 100 male and female persian efl learners with different proficiency levels (lower intermediate, intermediate, and advanced learners) in a university setting, who were placed at these levels based on their scores on a proficiency test. besides, 25 field observers were requested to gather instances of disagreement and disagreement strategies they observed or participated in for having a natural corpus of data. a discourse completion test (dct) was given to the participants of the study in order to determine whether and to what extent the realization of the speech act of disagreeing and politeness strategies differ in relation to people with different power status, social distance, formality of the context, gender, and proficiency level of persian efl learners. the disagreement taxonomy of rees- miller (2000) was employed for analyzing the disagreement responses and some new disagreement strategies were added to the taxonomy. the findings of this study provided some evidence for the relation between general factors of formality, power and gender and persian responses. also, gender and proficiency were proved to be effective for persian efl learners to express disagreement and applying politeness strategies while social distance for persian respondents and power, formality and social distance for efl learners did not provide a schematic template that could predict actual behavior accurately.