Abstract
The research problem is: Is there a relationship between reinforcement and student's learning interest in mastering vocabulary in class VII-B students of MTs Ma'had Tahfidz Mutiara Ilmu Kisaran, North Sumatra? This study aims to determine whether there is a relationship between reinforcement and student's learning interest in mastering vocabulary in class VII-B students of MTs Ma'had Tahfidz Mutiara Ilmu Kisaran, North Sumatra. The method used is a quantitative approach with the correlation method. The technique used to obtain research results is using statistical data with the Product Moment formula. And the results show that the relationship between reinforcement and students' learning interest in mastering vocabulary in class VII-B students of MTs Ma'had Tahfidz Mutiara Ilmu Kisaran, North Sumatra is 0.945. This figure indicates a strong relationship between the two variables with a positive direction. Therefore, it is found that the alternative hypothesis (Ha) is accepted and the null hypothesis (H0) is rejected. And finally, it can be seen that there is a relationship between the two variables.