Abstract: Motivation, as the extent to which the individual works or strives to learn a language, has been considered as the key variable in language learning (Gardner, 1985, Dörnyei, 2002) and motivating factors have been defined and studied as influential factors in the process of language learning. In line with other studies, the aim of this study was to investigate the main motivating factors among Iranian EFL at intermediate learners’ speaking ability. To this end, a sample of 100 Iranian EFL learners at two private language institutes studying English was selected. To gather the required data, the researchers used a PET (Quintana, 2003) and a motivation questionnaire in English. Repeated Measure ANOVA indicated eight motivating factors (i.e., determination, anxiety, extrinsic motivation, sociability, attitudes to culture, intrinsic motivation, beliefs about failure, and enjoyment) among which ‘determination’ was mentioned as the most motivating factor. The hope is that the findings help language teachers encourage motivating factors and among the learners.