Gender segregation is usually done in schools that are still within the scope of Islamic boarding schools. That contrast with the Salafiyah Simbangkulon Foundation, which not within the boarding school environment. Usually, segregation is applied when children enter MTs stage, while in Salafiyah Simbangkulon Foundation, segregation is carried out from children entering RA school. This paper will discuss how is the practices of gender segregation in Salafiyah Simbangkulon Foundation and what is the meaning of gender segregation in the Salafiyah Simbangkulon Foundation. The researcher uses the Living Qur’an method with sociology of knowledge approach in analyzing the data. First, their understanding of gender segregation is based on QS. Al-Ahzab verse 53 relates to the word “hijab”. The word “hijab” is attracted by the fact that there are boundaries between men and women in carrying out daily activities, including in education. From that understanding, they implemented it by holding gender segregation at the Salafiyah Simbangkulon Foundation. Gender segregation is applied to student and teacher. Between male and female student different classes and also different building that far enough away. Existing facilities and regulations assist the practice of gender segregation in the Salafiyah Simbangkulon Foundation. Second, Gender segregation has several meanings based on the Sociology of Knowledge approach. The objective meaning of gender segregation is that gender segregation itself is an obligation or routine that students and employess of the Foundation must carry out. The expressive meaning of gender segregation at the Salafiyah Simbangkulon Foundation, among others: to minimize the relationship between the opposite sex, professional in organization, not daring to have a relationship with the opposite-sex (dating). The documentary meaning of gender segregation at the Salafiyah Simbangkulon Foundation itself ia a form of preservation of the tradition of previous scholars, wherein Simbangkulon there used to be a very famous Islamic Boarding schools and was founded by Kyai Amir Idris. The existence of gender segregation also causes several adverse impacts as well as positive impacts for students studying at the foundation.