The present study investigated the effect of online collaborative project-based learning on the language performance and attitudes of intermediate level students at the College of Applied Sciences in Oman. The study is a quasi-experimental study and the sample consisted of four classes (93 students in total) in Nizwa College of Applied Sciences. These participants were in their foundation year and were taking the Academic English Course during the time of the research experiment. Two classes were assigned to the experimental group (46 students) and they were directed to collaborate online in doing their research projects. The other two classes were assigned to the control group (47 students) and did their projects individually. A language test containing reading and writing questions, an attitude questionnaire, students' project scores and transcripts of focused group discussions were used to collect the data needed to answer the research questions. The study revealed that the main positive effect of online collaborative project-based learning was clear on students' writing skill in the post test (i.e. students in the experimental group outperformed students in the control group). Al-Rawahi, L.S. & Al-Mekhlafi, A.M. (2015). The effect of online collaborative project-based learning on English as a Foreign Language learners' language performance and attitudes. Learning and Teaching in Higher Education: Gulf Perspectives, 12(2). http://lthe.zu.ac.ae 2 basic education systems into higher education colleges to come with experiences, expectations and abilities that can enable them to take part in Computer-Supported Collaborative Learning (CSCL). Efforts are already taking place to introduce more collaborative knowledge building practices in Oman; nevertheless, more support for students and faculty is still needed to encourage the use of CSCL tools in order to enhance this collaborative knowledge-building (Porcaro, 2011). Many researchers have recommended using project-based learning (PBL) as one way of learning and promoting various communication and collaboration skills (Tims, 2009; Pacific Policy Research Center, 2010; Patton, 2012). PBL is an instructional model that organizes learning around projects (Thomas, 2000). It is "a studentdriven, teacher-facilitated approach to learning" (Bell, 2010, p. 39), whereby students drive their learning through inquiry and collaborative work to investigate topics in order to reflect their knowledge (Bell, 2010). It is closely related to inquiry learning and constructivist learning (Lam, 2012). The use of projects is well established in education and it has recently developed into a formally defined teaching strategy. Projects are very useful because they put students in active roles such as problem solvers, decision makers or investigators. They also aid the achievement of many educational goals (Intel, 2007). Research on PBL shows that technology enables the development of critical thinking skills when students use technology tools to communicate, present and publish their proje...