The aim of this study was to investigate the impact of an educational program based on advanced organizers in developing critical thinking among the ninth grade students in the public schools of the Directorate of Education in Tulkarem for the academic year 2016/2017. In order to answer the study questions, the experimental method was used in its semi-experimental form. The study was applied to a sample of ninth grade students, consisting of 104 students, experimental group (52) students studied the chemical reactions unit using the advanced organizer; the control group (52) students studied the same unit in the usual method. To achieve the objectives of the study and for data collection purposes a critical thinking skill test was developed and the validity and reliability of the tool were verified before applying them to the study sample The results of the study showed the following: There was no statistically significant difference in the average performance of the experimental and the control group students in the test of post-critical thinking skills due to the gender variable (males and females). There was a statistically significant difference in the average performance of the experimental and control group students in the post-critical thinking skills test due to the interaction between teaching method and gender in favor of the female experimental group. Key words: Advanced Organizer, Critical Thinking, Science.