Classification is a central endeavor in every scientific field of work. Classification in biology, however, is distinct from classification in other fields of science in a number of ways. Thus, understanding how biological classification works is an important element in understanding the nature of biological science. In the present paper, I discuss a number of philosophical issues that are characteristic for classification in biological science, paying special attention to questions related to science education. My aims are (1) to provide science educators and others concerned with the teaching of biology with an accessible overview of the philosophy of biological classification and (2) to show how knowledge of the philosophy of classification can play an important role in science teaching.