Project-based learning (PBL) is an instructional method that has grown in popularity across all grade levels and subject areas, in both K-12 schools and higher education institutions. PBL embraces the integration of curriculum across subjects, the engagement of home and community in school learning, and the involvement of students in cooperative teamwork (Harada, Kirio, & Yamamoto, 2008). With regard to mathematics, specifically, advocates of project-based learning claim that problem solving skills are successfully developed when students learn mathematical content and process knowledge on their own in an authentic setting (Roh, 2003). This method of instruction has been adopted at a newly created public K-9 school system in its second year of operation in central Alabama. This study utilized a mixed methods approach (Creswell & Clark, 2017) to examining the implementation and assessment methods of project-based mathematics learning taking place in the middle grade levels (6-8) of this particular school system. In order to examine project-based learning implementation and assessment in middle grades mathematics classrooms in the school system of interest, data collection included student pre- and post-semester surveys, teacher post-semester surveys, multiple classroom observations, and existing data in the form of classroom grades and standardized test scores provided to the researcher by the school. The primary survey instrument utilized for this study was the Attitudes Toward Mathematics Inventory (Tapia & Marsh, 2004). The population of interest was 6th, 7th, and 8th grade mathematics students and teachers at the selected school system currently implementing and participating in project-based learning in mathematics classes. Research questions focused on topics such as: implementation and assessment of project-based mathematics learning; comparisons of classroom performance grading systems and standardized test results; relationships between student self-assessments, grades, and standardized test scores; and looking to identify significant increases in students' levels of self-confidence, value, enjoyment, and motivation in mathematics. Findings show that project-based learning is being implemented at different levels across the middle grades mathematics classes of the school. Some agreement was found between various assessment methods, but no significant increases were found in students' mathematics self-confidence, value, enjoyment, or motivation. [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.]