this study investigated how group formation method, namely student-selected vs. teacher-assigned, influences the results of the community model of teaching creative writing; i.e., group dynamics and group outcome (the quality of performance). the study adopted an experimental comparison group and microgenetic research design to observe the change process over a relatively short period of time. two intact classes of junior english literature students (n=32) participated in this study over one academic semester. community model was employed to teach creative writing to both classes, but the communities formed in the classes differed in terms of their grouping method. in other words, while in one class students (n=16) self-selected their working partners, in the other the teacher (based on the homogeneity of the students’ learning styles) assigned them (n=16) into groups. the data for this study were collected through students initial writing drafts, revised texts and an end of the course written report (for students to comment on aspects of group dynamics). one way repeated measures analysis of variance (anova) and content analysis were used for analyzing the quantitative and qualitative data respectively. the findings revealed a significant difference between the two group formation conditions regarding group outcome. in particular, although students of teacher-assigned group formation method reported no definite advantage over those of student-selected grouping in terms of group dynamics, they noticeably outperformed participants from student-selected grouping condition. however, the outcome of group works implies that teacher-assigned groups are more task oriented (a key aspect of group dynamics) and are thus more successful at accomplishing group task-here revision- (as evidenced by the quality of performance). in brief, the results suggest that group work as such does not guarantee success. group formation method also should be seen as a key factor contributing to the success of group work.