According to the National Science Education Standards (National Research Council 1996), students in the middle school years should progress in studying life science from examining individual organisms to recognizing patterns in ecosystems and developing an understanding about the cellular dimensions of living systems. Students should broaden the scope of their understanding from the way one species lives in its environment to populations and communities and the ways that various species interact with each other and their environment. These concepts are beautifully illustrated through the study of plant gall formation and gall communities. In this article, the author presents several science activities that involve observation of plant gall formation and gall communities. (Contains 5 figures and 10 resources.)