The aim of this study was to determine the effects of instructional materials development based on “Creativity Activities within a Group” on teacher candidates’ portfolios. This research was carried out with the two classes in the fall of 2007–2008 among 3rd year students enrolled in Faculty of Education’s Department of English Teacher Education. Quasi-experimental method was used and creativity-based material-development activities were applied to the experimental group. In the control group, individual materialdevelopment activities were put into practice. In both groups the teacher candidates prepared portfolios. There was a significant difference between the portfolio marks of the first and second group. The most powerful regressing item that regressed the portfolio marks of the students was the final marks at the end of the stepwise regression. 

Keywords: Creativity, Instructional Material Development, Portfolio, Group Works, Constructivism