The present study investigated demotivation among Iranian secondary school students. The necessary data were gathered from 604 secondary school male (N= 318) and female (N= 286) students. A 35-item demotivation questionnaire along with an item eliciting the participants' own assessment of their motivation to learn English was administered. Based on the results of a principal factor analysis, three factors, namely,(1) Inadequate School Facilities,(2) Improper Teaching Material and Content, and (3) Absence of Intrinsic Motivation were identified as the major demotivating factors for the language learners. Contrary to the results of previous research, however, teacher-related factors were not found as strong causes of demotivation. On the basis of the participants' own assessment of their motivation, they were divided into less and more motivated groups. Results of a mixed between within ANOVA and the follow-up tests indicated that Improper Teaching Material and Content was the main demotivating factor for both groups. The study may be of aid to Curriculum designers, material developers and those involved in the Iranian educational system.