The problem of this study is represented by one main question: what is the effect of implementing multi wikis in teaching the written composition on the developing some critical thinking skills and collaborative writing of first year secondary students? This main question includes the following minor questions: 1. What are the critical thinking skills there are suitable for teaching written composition using multi wikis to first year high school students? 2. What are the written composition topics suitable for first year secondary students? 3. What is the outline of the suggested program in teaching written composition using multi wikis on the development of some critical thinking skills and collaborative writing skills of first year secondary students? 4. What is the effectiveness of the language program based on the wiki used in developing the critical thinking skills and collaborative writing on teaching written composition to students? The sample was consisted of 40 students' secondary school taken from Ain Shams School for Males and 30 Arabic language teachers and supervisors. The results indicated that: 1. There are statistically significant differences between the observed and expected frequencies of the marks of Arabic language teachers and supervisors and Specialists in methods of teaching Arabic language in the items of the questionnaire of the critical thinking skills relevant for teaching written composition to first year high school students by using the multi wikis as k2 test shows. 2. There are statistically significant differences between the observed and expected frequencies of the marks of Arabic language teachers and supervisors in the items of the questionnaire of the Topics written composition relevant for teaching written composition to first year high school students by using the multi wikis as k2 test shows. 3. There are no statistically significant differences between the means of the experimental and control groups in the pre-test of critical thinking skills of written composition, students’ marks in the pre – test. 4. There are statistically significant differences between the means of students’ marks in the experimental and control groups in the post-test of critical thinking skills of written composition, students’ marks in the post- test.