Abstarct: This study investigates the effects of explicit instruction in cognitive and affective language learning strategies on vocabulary acquisition among Iraqi EFL learners. Vocabulary knowledge is fundamental to second language acquisition, yet Iraqi EFL learners often face significant difficulties in both vocabulary acquisition and retention due to traditional teaching methods that rely heavily on memorization and translation. While previous research has demonstrated the effectiveness of strategy instruction, most studies have examined cognitive and affective strategies in isolation, and limited empirical attention has been directed toward the Iraqi EFL context. To address this gap, the present study employed a quantitative quasi-experimental pre-test/post-test control group design with intermediate-level Iraqi EFL learners from a secondary school in Al-Basra. Participants were divided into three groups: two experimental groups (cognitive strategy training and affective strategy training) and a control group. Data were collected using the Strategy Inventory for Language Learning (SILL) and a researcher-developed Vocabulary Knowledge Test (VKT). The experimental groups received explicit strategy training over a two-week period integrated into regular vocabulary instruction, while the control group received regular instruction without strategy training. The results revealed that both cognitive and affective strategy training had significant positive effects on vocabulary acquisition, with the cognitive group demonstrating the highest vocabulary gains, followed by the affective group, while the control group showed minimal improvement. However, no statistically significant difference was found between the two experimental groups, indicating that both types of strategy training were equally effective. These findings challenge the conventional emphasis on cognitive strategies alone and suggest that affective strategies play an equally important role in vocabulary learning. The study contributes theoretically by extending Oxford's (1990) taxonomy of language learning strategies to the Iraqi EFL context and providing empirical evidence for the complementary roles of cognitive and affective strategies in vocabulary acquisition. Practically, the findings offer valuable implications for language teachers, curriculum developers, and policymakers in Iraq, suggesting that strategy-baxsed instruction should be integrated into vocabulary teaching to foster learner autonomy and improve learning outcomes. By equipping learners with effective cognitive and affective strategies, educators can help Iraqi EFL learners overcome the challenges they face in vocabulary learning and become more autonomous, self-regulated, and successful language learners.