Today Web 2.0 technologies, including blogs, are presenting both teachers and learners with new horizons in the field of language teaching and learning. A blog is an online journal which can be continuously updated by its users [Matheson, D. (2004). Weblogs and the epistemology of the news: Some trends in online journalism. "New Media & Society, 6", 443-468.]. Blogs are easy to construct without the need of understanding HTML, and their appearance and content can be enhanced through the use of pictures, audio and video files. Due to their asynchronous nature, blogs allow people to write and publish their thoughts and views at their own pace without space and time constraints. In language learning, the use of blogs is considered to be similar to that of journal writing [McLeod, 2001; as cited in Lowe, C. (2004). Moving to the public: Weblogs in the writing classroom. "Into the Blogosphere". Retrieved April 16, 2009, from http://Blog.lib.umn.edu//blogosphere/moving_to_public_pf.html]. Hence, students use the basis of their worldviews to shape and interpret their own meanings in writing. Using task-based activities to encourage students' interaction, the present study explores how a blog as a computer-mediated tool engages a group of English as a Foreign Language learners at a language school in Spain in reflective and collaborative learning. Eleven students who were preparing for the Certificate in Advanced English (CAE) Cambridge examination were involved in a study that lasted for five months. All the participants created their personal blogs so that they could read each other's views, share ideas and comment on their peers' postings. The activities focused on the specific writing tasks (letter writing, report, proposal, article, etc.) comprised in the aforementioned examination. Consequently, the project aimed to (1) enhance writing skills in specific writing tasks, (2) perceive the effect of the learners' feedback and (3) foster collaborative skills. Drawing on the triangulated data collated from the blog entries, class discussions based on peers' feedback and questionnaires, this paper argues that personal blogs can motivate students to build their writing skills through self-reflection and peer feedback. The engagement in negotiation of meaning between peers led to better planning and the choice of the right register/style required in each task prior to writing and submitting their work. Collaborative skills were also fostered through students' regular interaction in the blogs. For meaningful learning to take place, pedagogical intervention could encourage students to take their peers' comments into account so that they can edit their own work with a view to enhancing their writing tasks and producing mistake-free texts. (Contains 3 tables, 1 figure and 2 notes.)