This study was supported by the lack of students' critical thinking skills and self-confidence. The study aimed to improve the critical thinking skills and self-confidence of students through the Discovery Learning model. This classroom action research consisted of two cycles and underwent two meetings in each cycle. Every cycle, there were four stages; planning, implementing, observing, and reflecting. The research subjects were 29 students in grade V SD Negeri Karangsalam from 16 male and 13 female. The data collection instruments were evaluation tests, students 'critical thinking skills, students' self-confidence observation sheets, teacher observation sheets, and student activity observation sheets. The improvement can be seen in each cycle. In the first cycle, the students' critical thinking skills obtained an average score of 73.2 or in good criteria and the second cycle obtained 78.7 or in good criteria. The results of students' self-confidence illustrated an improvement in cycle I to cycle II. The self-confident attitude of the students in the first cycle obtained an average of 73.1 or in good criteria and 83.7 in the second cycle or in very good criteria. The results indicated that the implementation of the Discovery Learning could improve students' critical thinking skills and self-confidence in theme 8 "Lingkungan Sahabat Kita" for grade V SD Negeri Karangsalam. The improvement of critical thinking skills and students' self-confidence occurred because the teacher followed the steps of the Discovery Learning model correctly.