The study examines whether there is any difference between the effects of a reading–writing integrated task and comprehensive corrective feedback (CF) on English as a foreign language (EFL) learners’ writing development, and whether the input language in the integrated task makes a difference in L2 writing development over time and the language accuracy of the writing resulting from the integrated task. It also explores the possible relationships among language, content alignment and language accuracy and the relationship between language alignment and content alignment. To this end, a quasi-experimental study was conducted to assess participants’ L2 writing development based on a pretest–posttest–delayed-posttest design implemented in four intact EFL freshman classes. Four groups were created: an English-reading–English-writing (EE) group, a Chinese-reading–English-writing (CE) group, a comprehensive CF group, and a control group, which engaged solely in writing practice. The results demonstrated that (1) the EE and CF groups outperformed the control and CE groups on the posttest and outscored the control group on the delayed posttest with respect to language, although there were no significant differences among the three experimental groups in overall, content, and organization scores; (2) the input language of the integrated reading–writing task had a significant effect on language accuracy in the resulting essays; and (3) there was no significant correlation between content alignment and language accuracy for the CE group, whereas for the EE group, a significant positive correlation was observed not only between content and language alignment, on the one hand, and language accuracy, on the other hand, but also between content alignment and language alignment.