The study was development research that aimed to develop four competence-based thematic teaching materials in the 21st-century students in theme 8 about our friend's environment and sub-theme 3 about environmental conservation efforts of learning 1 in grade v primary school. The objects of this development were the teacher books and student books of Ministry of Education and Culture, Bupena, and student worksheet. This study used a Research and Development (R&D) type of research using 4-D research steps according to Thiagarajan, Semmel, Semmel, namely define, design, develop. This study was limited only to the development step, namely product assessment of the validator and teacher assessment. The data were collected by using questionnaires that were distributed to the experts of material, language, and learning as well as a teacher questionnaire. In fact, it was necessary to develop four competence-based thematic teaching materials in the 21st-century students in order to make the previous thematic teaching materials perfect. The validation of the teaching materials obtained the meant score of 3.5 on the first step with a valid criterion. In the second step, it obtained 4.4 with a very valid criterion. The teacher evaluation of the materials obtained the mean score of 4.0 with a good criterion. Based on the results, the four competence-based thematic teaching materials in the 21st-century students were able to be used.