Systemic functional linguistics (SFL) was the foundation for this study that explored the effect of science text and image integration on grade 9 students' reading comprehension. Two texts in Chinese on the moon phase with different print and image integration were compared--a traditional textbook (TT) used in Taiwanese junior high schools and a systemic functional linguistics text (SFLT) created by the authors for this study. These two texts contained similar concepts but had major differences in several features: technicality, representational structure, degree of modality, and interaction between print and image. A control-experimental design with pretest, posttest, and semi-structured interviews was used. In total, 132 junior high school students were randomly assigned to two groups: one group (n=69) read the TT and the other group (n=63) read the SFLT. Sixteen students with both high and low performances in the posttest were purposely selected as the subjects of the follow-up interviews. Major findings were: (a) students who read the SFLT demonstrated significantly better achievement than those who read the TT, and (b) students who read the TT generated more misconceptions about the moon phase and had greater difficulty in making sense of the images than the students who read the SFLT. Accordingly, SFL may serve as a useful theoretical framework and tool in the design of textbooks and may have a practical application in the science classroom.