ABSTRAK Penelitian ini bertujuan untuk menginvestigasi pengaruh penerapan model Contextual Teaching and Learning (CTL) berbasis diferensiasi di kelas 10 SMK. Metode penelitian yang digunakan adalah desain penelitian satu kali uji (pretest-posttest). Subjek penelitian adalah siswa kelas 10 SMK di SMK Taufiq Mubarok. Instrumen yang digunakan adalah tes pengetahuan sebelum (pretest) dan setelah (posttest) perlakuan. Data dianalisis menggunakan uji Mann-Whitney. Hasil menunjukkan adanya perbedaan signifikan dalam nilai siswa sebelum dan setelah penerapan model CTL, mendukung efektivitasnya dalam meningkatkan pemahaman dan prestasi siswa. Kata kunci: Model CTL, diferensiasi, kelas 10 SMK, pretest-posttest, uji Mann-Whitney THE EFFECT OF APPLYING DIFFERENTIATION-BASED CONTEXTUAL TEACHING AND LEARNING MODELS IN GRADE 10 HIGH SCHOOL ABSTRACT This study aims to investigate the effect of applying a differentiation-based Contextual Teaching and Learning (CTL) model in grade 10 high school. The research method used is a one-time test research design (pretest-posttest). The subject of the study was a grade 10 high school student at SMK Taufiq Mubarok. The instruments used are knowledge tests before (pretest) and after (posttest) treatment. Data were analyzed using the Mann-Whitney test. Results showed significant differences in students' scores before and after the application of the CTL model, supporting its effectiveness in improving student understanding and achievement. Keywords: CTL model, differentiation, grade 10 high school, pretest-posttest, Mann-Whitney test.