Wikis, as one of the Web 2.0 social networking tools, have been increasingly integrated into second language (L2) instruction to promote collaborative writing. The current study examined and compared summary writing abilities between students learning by wiki-based collaboration and students learning by traditional face-to-face collaboration. The experimental research was conducted with students enrolled in EN 111 course in the first semester of academic year 2011. The instruments employed in the study were summary writing tests, a questionnaire, and products of summary writing. Data were analyzed by using means, standard deviations, percentages, and t-tests. The results indicate that the post-test scores of both groups were significantly higher than the pre-test scores (p less than 0.05). However, no significant difference was found between the two groups' writing mean scores and satisfaction with the learning methods. In addition, the writing products which students in both groups submitted were not different in quality. Although there were minor drawbacks, a lot of advantages were identified, showing students' positive attitudes towards learning through wiki.