Abstarct: This mixed-methods study examines the effect of humor-integrated grammar instruction on Iraqi EFL learners' acquisition of English grammar, while also investigating how humor is operationalized as an instructional strategy through teacher self-reflection. Using a pretest-posttest control group design, 63 intermediate-level university students were assigned to an experimental group (humor-baxsed instruction, n=32) and a control group (traditional instruction, n=31). Parallel grammar tests measuring conditional structures were administered before and after a 12-week instructional period. To address the instructional process dimension, the teacher-researcher engaged in systematic reflective documentation throughout the intervention, recording humor strategies employed, learner responses, and comparative classroom dynamics between groups. Statistical analysis revealed significant improvement in both groups, but the experimental group demonstrated substantially greater gains. The experimental group's mean gain score was 9.06 compared to 4.81 in the control group, with a statistically significant difference (p < .001) and large effect size (Cohen's d = 2.30). Qualitative analysis of reflective documentation identified four distinct humor strategies used by the teacher: (1) humor for grammatical presentation and rule explanation, (2) humor for contextualizing grammatical meaning, (3) humor for modeling creative language use, and (4) humor for affective scaffolding and classroom climate management. These qualitative insights contextualize the quantitative findings by illuminating the pedagogical mechanisms through which humor exerted its effects. Together, the findings provide empirical evidence that humor-integrated instruction is more effective than traditional methods in enhancing grammatical achievement, while also offering a replicable model of how humor can be systematically deployed as an instructional strategy. The study contributes to EFL pedagogy by demonstrating both the quantifiable benefits of humor in grammar instruction and the specific instructional practices through which these benefits are realized.