This case study aimed to apply the values-engaged approach to evaluate the impact of the Self-Regulated Strategy Development writing program (SRSDP) on the Grade 5 students, including the application of writing self-regulated strategy, writing motivation, and writing performance. The participants consisted of 26 Grade 5 students from the same class. The SRSDP had been implemented for 12 weeks. During the research period, based on the core perspective of values-engaged approach to evaluation, the researchers, particularly concerned with the experience and perception of those least well-served students. The data were collected through quantitative and qualitative approaches, composing of the Scales of Writing Self-Regulated Strategy, Writing Motivation, and Writing Performance, students’ worksheets, feedback sheets, and group focused interview. Quantitative Data analyses included descriptive analysis and dependent sample t-test. Qualitative data analyses consisted of organizing data, coding data, and analyzing and interpreting data. The study found that SRSDP provided remarkable positive influences on lower-level and middle-level students’ writing performance and their application of the application of writing self-regulated strategy. SRSDP also brought wonderful writing and learning experiences to the lower-level students. Based on the findings, the conclusion and discussion were also made in the study.