Classroom Action Research entitled Improving Learning Outcomes of Catholic Religious Education Through Problem-Based Learning Methods for Unique Me Material Phase B of Class IV of SD N 030426 Lae Tarondi, Pakpak Bharat Regency. This was conducted to improve the learning outcomes of students in class IV phase B of SD Negeri 030426 Lae Tarondi, Salak District, Pakpak Bharat Regency. The research was conducted by implementing the Problem Based Learning (PBL) learning method. Problem-based learning (PBL) is a student-centered learning model that has been widely known. Although it has been widely known, teachers and prospective teachers need to know the theoretical basis of PBL, the characteristics of PBL, and things that need to be done before and during the implementation of the PBL model. This article aims to explain the theoretical basis of Problem-Based Learning, the characteristics of the Problem-Based Learning model, and the implementation of the Problem Based Learning model. The method used in writing is a literature review. The focus of the study is on the theoretical basis of Problem-Based Learning, the characteristics of the Problem-Based Learning model, and the implementation of the Problem Based Learning model. The results of the study show that in addition to the theory of constructivism, the theoretical basis for PBL is Piaget's Cognitive Development Theory, Dewey's Theory, Bruner's Theory of Discovery Learning. Before implementing PBL, teachers need to train students to learn cooperatively. (Ardianti et al., 2021a)