Abstarct: The majority of learners in Iraqi EFL classes are low achievers who frequently experience repeated academic failure that negatively affects their academic self-concept and motivation; however, few studies have focused on instructional strategies to overcome the negative consequences of academic failure on learners' self-concept and motivation. The present study was mixed methods research that aimed at knowing the effect of tiered classification methods on academic self-concept and motivation of secondary school 9th grade students who have low achievement levels in Iraqi secondary schools. A convergent mixed-methods design was used that included a quasi-experimental pretest-posttest control group design with an experimental group of 42 subjects and a control group of 42, and a focus group interview with a sub-sample of 12 low-achieving learners from the experimental group. The six-week intervention was a tiered tasks (Tier 1, Tier 2, Tier 3) that were flexible and baxsed on the needs of the students; regrouping occurred weekly baxsed on formative assessment. The quantitative results indicated that the experimental group had a statistically significant increase in academic self-concept (mean change +1.19, p< .001, Cohen's d = 1.86), whereas the control group did not show any statistically significant change (+0.12, p= .134). Through thematic analysis of qualitative data, five themes emerged: psychological safety and reduced anxiety, challenged learning that is appropriate, increased willingness to communicate, positive shifts in self-perceptions, and preference for tiered groupings over traditional groupings. The findings will provide the first context specific evidence in Iraq that tiered grouping strategies improve the academic self-concept and motivation of low achieving students and will add to the pedagogical practices that may be implemented on a practical level in low resource EFL classrooms in Iraq to help meet the needs of learner diversity.