The purpose of this study was to compare growth in student achievement of students in a classroom where the assessment for learning process was either absent from or present in a teacher's practices, and to gather the teacher's and students' perceptions of the benefits and barriers related to growth in student achievement when the assessment for learning process is either absent from or present in the classroom. The related research questions were: (1) How does growth in student achievement compare in a classroom where the teacher implements the assessment for learning process, to a classroom where the teacher does not implement the assessment for learning? (2) What are the teacher's perceptions of the benefits and barriers related to growth in student achievement in a classroom where the assessment for learning is present, and in a classroom where that process is absent? (3) What are students' perceptions of the benefits and barriers related to their achievement growth in a classroom where the assessment for learning is present, and in a classroom where that process is absent? The research approach of this study was a quasi-experimental comparative case study using mixed-methods to resolve the research questions. Data were collected through the methods of interview, focus group, document review, and observation. Quantitative data were analyzed using an ANCOVA to compare growth in student achievement. Qualitative data were analyzed using the seven phases for qualitative data analysis recommended by Marshall and Rossmann (2006). The results of the ANCOVA were not statistically significant. However, the calculated effect sizes illustrated the potential for enough practical significance that might support the benefit of the assessment for learning process on students' growth in achievement. Through analysis of the qualitative data collected, the researcher identified perceived benefits and barriers to student achievement, as well as major themes related to assessment, grading, feedback, instruction, homework, student motivation, and teacher's disposition. The research findings led to the conclusion that school leaders need to provide teachers with knowledge and training related to best practices, as well as engage them in professional development that promotes self-reflective practice of those strategies. [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/en-US/products/dissertations/individuals.shtml.]