If students are to be successful in the ever-changing scientific world they need to be taught how to think critically, to manipulate materials, and to gather evidence to build knowledge. Most teachers fall short in providing students the inquiry instruction described in the Next Generation Science Frameworks (National Research Council, 2011). This study examined three elementary science teachers' processes as they developed inquiry practices over time. The Electronic Quality of Inquiry Protocol (EQUIP) was used to gather quantitative and qualitative evidence of the teachers' inquiry practices in terms of four factors, "Curriculum," "Instruction," "Discourse," and "Assessment." A chronological analysis was used to examine the teachers' professional development and curriculum experiences in relation to their teaching practices. The results showed that all three teachers did change their practice, although the changes varied among cases. For each case, multiple factors influenced the teacher's development. There was a strong positive correlation between the quality of the teachers' inquiry practices and the time spent in curriculum-contextualized professional development. This research indicates that when teachers are supported with curriculum and professional development over extended periods, they develop exemplary inquiry practices. Three recommendations are provided for those interested in implementing science education reform. [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://www.proquest.com.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]