摘要:This study explored the effect of portfolio and self assessment on writing tasks on the one hand and self regulation ability on the other by assigning sixty freshman undergraduate university students majoring in teaching English as a foreign language to a control and experimental group. They had enrolled in the Writing Essay course at Tabaran University in Iran in 2010. While both groups wrote several essays during the course and took a self regulation questionnaire and the same writing task at the beginning and end of the course as pre-and-post tests, only the participants in the experimental group were required to write portfolios regularly and perform self assessment tasks. The multivariate analysis of results showed that the two groups had no significant difference in their writing and self-regulation abilities when the course started. The experimental group, however, did not only score significantly higher than the control group on the writing task (F = 14.390, df = 1, p <.000) but also gained higher self regulation ability as a result of writing portfolios and self assessment (F = 58.235, df = 1, p <.000). The implications of the study are discussed within a foreign language teaching context.