This study investigated the development and sustained development of grammatical and lexical accuracy in three writing modalities of individual, collaborative and e-collaborative writing. To this end, 90 Iranian Intermediate EFL learners were selected according to the participants' scores on a writing pretest.. Participants were assigned into the research groups e on the basis of convenient sampling. The writing performances in three groups of individual, collaborative and e-collaborative writing performance were measured on pretest, posttest and delayed posttests. Multivariate analysis of variance (MANOVA) indicated that participants’ writing performance in individual writing F (5, 38) = 16.06, p = .000, partial η2 = .679 representing a large effect size) and collaborative writing (F (5, 38) = 17.64, p = .000, partial η2 = .699 representing a large effect size) were sustainably improved in terms of grammatical and lexical accuracy. MANOVA results also indicated that participants writing performances in E-collaborative writing (F (5, 38) = 8.64, p = .000, partial η2 = .532 representing a large effect size) were improved and the improvement was sustained with respect to grammatical accuracy but not lexical accuracy. The post hoc comparison indicated that that collaborative writing was the most effective mode of writing as far as grammatical and lexical accuracy were concerned. The results have significant implications for teaching practitioners.