Writing is an indispensable part of any language learning process, the mastery of which requires a lot of time, effort, and energy. The process of writing itself is always influenced by some factors that may lead to individual differences. Among those contributing factors, the learners' beliefs along with peer vs. teacher ratings have been taken into account in this research. Ninety intermediate Iranian EFL learners studying English at Shayestegan English Language Institute in Tehran participated in this study. The homogenized sample of the study was selected based on their scores on the Michigan English Language Test. Then six writing assignments along with the general learners’ belief scale designed by Horwitz (1988) were administered to the participants. The participants’ writing assignments were scored analytically according to Jacob et al.’s scale (1981) once by the teacher and once by the peers. The results of the correlational analyses revealed that there was a statistically significant difference between the mean of ratings of teachers and peers. In fact, rating types had a significant but small effect on writing scores of the participants. To investigate the relationship between learners’ beliefs and their writing performance, a series of Pearson Product Moment Correlation Coefficients were estimated. The results of the analyses indicated that there was no significant relationship between students’ beliefs and their writing performance when it was rated by peers and/or the teacher. The pedagogical implications and suggestions for further research were also proposed.