This article examines the application of Krashen’s Second Language Acquisition hypotheses to differentiated instruction in a TESOL context. The study is based on the analysis of two learner profiles representing contrasting linguistic backgrounds, affective factors, and learning preferences. Using the Input Hypothesis, Affective Filter Hypothesis, and Monitor Hypothesis as an analytical framework, the paper demonstrates how theoretical principles can inform practical classroom decisions. The findings suggest that contextualized input, emotionally supportive learning environments, and fluency-oriented tasks play a crucial role in facilitating effective language acquisition. The study contributes to practice-oriented TESOL research by illustrating how SLA theory can be operationalized through learner-centered instructional design.

TESOL, second language acquisition, Krashen’s hypotheses, learner profiles, affective filter, differentiated instruction

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