This study explored the characteristics of elementary science teachers who employ reforms-based practices. Particular attention was paid to the consistency of teachers' practices and their beliefs, the impact of professional development experiences on practices, and how teachers mitigated barriers to reforms-based instruction. Understanding how successful elementary science teachers develop fills a gap in the science reforms literature. Participants included 7 upper elementary science teachers from six different schools. All schools were located within two suburban school districts in the south-Atlantic United States and data was collected during the spring of 2008. Data collection included use of the Reformed Teaching Observation Protocol (RTOP) to evaluate the level of reforms-based instruction, as well as 35 hours of classroom observation field notes and 21 hours of audio-taped teacher interviews. The variety of data sources allowed for triangulation of evidence. The RTOP was analyzed using descriptive statistics and classroom observations and interview data were analyzed using Erickson's (1986) guidelines for analytic induction. Findings indicated (a) reforms-based elementary science teaching was attainable, (b) beliefs and practices were consistent and both reflected reforms-based philosophies and practices, (c) formal professional development experiences were limited and did not foster reforms-based practices, (d) informal professional development pursued by teachers had a positive impact on practices, (e) barriers to reforms-based instruction were present but mitigated by strong beliefs and practical strategies like curriculum integration. These findings suggest that there are common, salient characteristics of reforms-based teachers' beliefs, practices, and professional development experiences. These commonalities contribute to an understanding of how reforms-based teachers develop, and inform efforts to move all elementary teachers in the direction of reforms-based science teaching. [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.]