The purpose of the present study was first to offer a tentative solution to the problems observed in writing pedagogy in Iran by devising a more comprehensive approach to genre-based writing instruction. In the second phase, a quasi-experimental research design was adopted to determine how effective the model was in writing instruction, compared with the traditional, product-oriented approach, as well as Swales’ genre-based approach. The participants were selected randomly and then divided into three groups: A control group (CG) (N=8) that received product-oriented instruction, Swales’ model (SM) group (N=8), and the system-nested, genre-oriented, structurally mediated model (SGSM) group (N=7). The results obtained through One-way ANOVA revealed that the SM group outperformed the CG group on the posttest of writing. Moreover, the SGSM group outperformed the other two groups on the posttest of writing. The pedagogical and theoretical findings of the study were then discussed.
