Effective science teachers use curriculum materials as a guide in their planning, critiquing and adapting them to promote inquiry-oriented, standards-based teaching and address specific contextual needs. Unfortunately, many preservice teachers encounter difficulties with these design tasks, making changes that are inconsistent with science education reform efforts or failing to make much-needed modifications. To help them become well-started beginners in analyzing curriculum materials, preservice teachers need opportunities to develop their pedagogical design capacity--that is, their ability to use their knowledge and beliefs, along with resources within curriculum materials, to design instruction for students. However, how teacher educators can support preservice teachers in developing this capacity has been largely unexplored in the literature. This dissertation addresses this gap by investigating the use of reform-based criteria in scaffolding the development of an analytical stance toward curriculum materials. Twenty-four preservice teachers from one section of an elementary science methods course participated in this study, with a subset of seven followed into their student teacher semester. In learning about and applying criteria during the course, the preservice teachers developed aspects of their pedagogical design capacity for curricular planning. Many of them adopted a criterion-based approach to analysis, expanded their analysis ideas, and refined their beliefs about curricular analysis. However, the preservice teachers struggled with engaging in authentic analysis tasks during the course and maintaining a principled, reform-based approach to analysis during student teaching. This may have occurred, in part, because the scaffolds within the course were faded before the preservice teachers could develop the capacity to engage in curricular planning on their own using curriculum materials from their field placements, which tended to be poorly aligned with reform-based science teaching goals. This finding may also have occurred because their cooperating teachers expressed different reasons for adapting materials than what was presented in the course. The methods course emphasized the importance of modifying materials to make them more consistent with reform-based practices, but few preservice teachers observed teachers make adaptations for this reason. These findings have important implications for theoretical models on curriculum materials use and the design of science teacher education and curriculum materials. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]