The purpose of this study was to detect the extent to which contextual material of a unit on "The origin and evolution of living organisms" included in the high-school biology curriculum in Jordan affected students' acceptance of the theory of evolution. The participants of this study consisted of 107 tenth-grade students randomly drawn from three girls public high schools affiliated with the Amman Directorate of Education II, during the first semester of the scholastic year 2008-09. Results revealed that the prime factors that are related to students' conviction that evolution took place were their prior belief that evolution occurred, followed by their appreciation of the importance of studying evolution. Concerning the effect of studying the evolution unit on convincing the students that evolution took place, the results showed that the majority of the students indicated that the Qur'anic verses and the section on "Natural selection" contributed to their conviction that evolution took place. The findings of this study can have useful implications for developing and evaluating high-school biology curriculum and instruction. (Contains 6 tables.)