This study has devoted itself to examining the effect of using cloud-based collaborative writing on EFL students' writing quantity and quality. Twenty-one EFL students studying at Jubail College of Education, IAU University participated in the study. They were pretested in writing quantity and quality before the treatment then they practiced cloud-based collaborative writing for a whole semester before being posttested in both measures. Results from non-parametric Wilcoxon Signed Ranks revealed no significant difference between the pretest and the posttest regarding writing quantity whereas it revealed a significant difference with regard to writing quality. It was concluded that cloud-based collaborative writing can be used to improve the quality of essays written by EFL students. Recommendations and research suggestions were introduced.Through the researcher's experience as an associate professor of TEFL at Jubail College of Education, IAU University, she noticed that writing is indeed a problematic area for most EFL students and that most students get low grades in their writing exams. Furthermore, she administered a writing test to a group of these students. Through analyzing their answers, the researcher found that they wrote insufficiently and she discovered that they committed many errors in coherence, grammar, spelling, structure, word choice, punctuation, phoneme clusters, and use of prefixes and suffixes. Therefore, the need arose to search for a solution for Saudi EFL students' inability to write effectively regarding both quantity and quality. Based on the researcher's search for effective strategies that can improve EFL writing quantity and quality, cloud-based collaborative writing seemed as a promising one.