The research aims to investigate the effect of philosophy education for children in social studies course on students' conceptual success and critical thinking skills. Sequential descriptive model, one of the mixed methods research approaches, was used in this study. The study group of the research consists of 64 students studying in 5th grade in a secondary school affiliated with the Ministry of National Education located within the provincial borders of Istanbul city. The students included in the study group studied in the same primary school. The students were randomly selected by the researcher considering their primary school grade score averages, gender characteristics and their economic conditions. Quantitative data of the study were collected using Conceptual Achievement Exam and Critical Thinking Skills Scale, on the other hand qualitative data was collected using Semi-Structured Interview Form. In order to reveal the effects of philosophy education practices for children on students' conceptual success and critical thinking skills, a 10-week practice was conducted in the context of “Technology and Life” unit in 5th-grade social studies course book. Quantitative data of the research were analyzed with SPSS package program, and qualitative data were analyzed with MAXQDA program. According to the results of the research, before practices of Philosophy Education for Children, no significant difference was found between mean rank of experimental group's Conceptual Achievement Exam and Critical Thinking Skills Scale pre-test scores and control group's Conceptual Achievement Exam and Critical Thinking Skills Scale pre-test scores. After the practices of Philosophy Education for Children, a significant difference was found between mean rank of experimental group's Conceptual Achievement Exam and Critical Thinking Skills Scale post-test scores and control group's Conceptual Achievement Exam and Critical Thinking Skills' post-test scores on behalf of the experimental group. Experimental group students made a comprehensive evaluation of practices of philosophy education for children. The students stated that philosophy practices for children not only improved their skills in different ways but influenced their critical thinking and also creative, social, verbal and empathy skills as well.