Decentralization of educational policy offers schools and teachers possibilities to take initiatives to alter (parts of) their curriculum. Instead of adhering to pre-defined programs, they are enabled to renegotiate and redesign their curriculum. The Dutch educational policy context (with its tendency towards increasing autonomy of schools) offers a rich field to study schools that are renegotiating their school curriculum. Influenced by the increase in autonomy, there is a growing number of schools that strive to renew their existing curriculum and school organization.Within this context, there is a need for suitable methods (procedures, instruments and activities) that stimulate school-based developments towards a new coherent curriculum. In our study we aim at contributing to this field. While doing so, we take as a major principle that successful en sustainable school-based curriculum renewal efforts need synergy and productive relations between: 1. curriculum development at various levels (system, school and classroom); 2. professional development of teachers; and 3. school development (cf. Fullan, 2001; Hopkins, 2001). Moreover, we take as a starting point that teachers seem to have a central role in de curriculum design processes (Black & Atkin, 1996; Clandinin & Connelly, 1992; Grossman & Stodolsky, 1995; Skilbeck, 1998) and, in order to realize synergy, collaboration among teachers seems to be indispensable for schools that are working towards a more relevant and coherent curriculum (Hargreaves, 2003; Hord, 2004; Lieberman & Miller, 2004; Little 1990; McLaughlin & Talbert, 2006). The study that we report on in this paper centers on the potentials of teacher design teams (TDTs) as a means to integrate curriculum development, teacher development and school development. TDT's are groups of teachers of related subjects who cooperate in order to renew and redesign their common curriculum and to develop themselves professionally (at the individual, group and school level). They not only redesign but also commonly implement the new curriculum in their classes. In this context, teacher collaboration is seen as essential to bridge the gap between the work of individual teachers (within their own subjects and classrooms) and school-wide aspirations.The main research questions in this study were:a. What curriculum design activities (including analysis, design, evaluation and implementation activities) do teachers, team leaders and school leaders carry out when redesigning the curriculum?b. Which activities are considered beneficial from their perspective when redesigning their common curriculum? Although there is considerable research data showing that collaborative teacher teams are beneficial for student learning, much less is known about how such teams start and are sustained in their work (cf. McLaughlin & Talbert, 2006). Literature offers many models and strategies for curriculum development, however, in daily practice, teachers tend to base their design decisions (on matters like fruitful learner activities, relevant content, suitable resources, appropriate timing, et cetera) predominantly on their practical knowledge (what will and will not work in the classroom), including personal survival concerns and beliefs about professional identity (Black & Atkin, 1996; Olson, 2002; Walker, 2003). Nevertheless, when teachers are working together as a team on the redesign of their curriculum, more efforts need to be put into discussing the ideas and consequences and finding ways to come to an agreement. These are topics that will be dealt with in this study. In order to answer the research questions, TDT's were followed within different school settings and different aspects of their design work were examined and compared. The main research methods were observations of the activities of the teacher teams and reflective (group) interviews with teachers, coaches and school leaders. During the interviews, the emphasis was put on critical events in the process, the support that the team received, and on the results of the process in the form of products and the impact on the team and individual teachers. Through a process of case analysis (analysis of the process within a team), in site cross-case analysis (comparison of teams within one school site), and cross-case analysis (comparison between different school sites), patterns, conditions, and effective activities within these teams were exposed.The process of cross-case analysis is now in progress and in the paper we will present the conclusions of this analysis. . Black, P. & Atkin, J. M. (Eds.) (1996). Changing the subject. Innovations in Science, Mathematics, and Technology Education. London: Routledge.Clandinin, D. J. & Connelly, F. M. (1992). Teacher as curriculum maker. In P. Jackson (Ed.), Handbook of research in curriculum, pp. 363-401. New York: MacMillan.Grossman, P., & Stodolsky, S. (1995). Content as context: The role of school subject in secondary school teaching. Educational Researcher, 24(8), 5-11.Hargreaves, A. (2003). Teaching in the knowledge society. Education in the age of insecurity. 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