Due to the increased demands for accountability with the passage of the No Child Left Behind legislation signed in 2002 by President Bush, schools are required to use reading strategies and programs that are supported by scientific research. In Arizona state statute, ARS 15-704, the law outlines the requirements for Arizona school districts to follow when teaching kindergarten through third graders to read. Some of these requirements include adopting a reading curriculum that incorporates the five essential components of reading (phonemic awareness, phonics, vocabulary, fluency, and comprehension), the use of an assessment system to screen and monitor students, and on-going teacher training focused on scientifically based reading research (SBRR). This study examined the differences in kindergarten and first grade students' reading achievement on the Dynamic Indicators of Basic Early Literacy Skills (DIBELS), assessments that measure early literacy skills, in schools where teachers were provided forty hours of scientifically based reading research (SBRR) professional development with follow-up literacy coach support and in schools where teachers were not provided this training. Schools in Pinewood School District, a fictitious school district name, chose to attend training; however, all kindergarten and first grade staff and building administrator had to commit to attending as a group. A review of the literature included information about teacher professional development, reading instruction, and DIBELS. Professional development is defined and a brief history of professional development is discussed. Traditional professional development is contrasted with best practices in teacher professional development. The next section describes the historical background of reading instruction in the United States. This section ends with a history and description of DIBELS. Six of nineteen schools in the Pinewood School District were included in the sample. Teachers in three schools participated in the forty-hour training and teachers in the other three schools did not participate in training. The sample included 523 kindergarteners and 517 first graders. To analyze pre- and post-assessment data for DIBELS measures PSF (K and 1), NWF (K and 1), and ORF (1) for December 2008 and May 2009, several ANCOVAs were used. Data were disaggregated by cluster, gender, ethnicity, and poverty levels for each grade level and DIBELS measure. The factor was teacher training, the dependent variable was DIBELS post-test scores, and the covariate was DIBELS pre-test scores. The analyses showed mixed results. For some disaggregated groups, there was a significant relationship between teacher training and DIBELS post-test results. A chi-square analysis was used to evaluate the relationship between teacher training and students' DIBELS instructional support recommendations in May 2009. There were significant results on this analysis. Results of all analyses were reported. The study concludes with a summary of all chapters and findings, conclusions based on the findings, and recommendations for practice and future research possibilities. [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.]