The philosophy of biology has existed as a distinct sub-discipline within the philosophy of science for about thirty years. The rapid growth of the field has mirrored that of the biological sciences in the same period. Today the discipline is well represented in the leading journals in philosophy of science, as well as in several specialist journals. There have been two generations of textbooks and the subject is regularly taught at undergraduate as well as graduate level. The current high profile of the biological sciences and the obvious philosophical issues that arise in fields as diverse as molecular genetics and conservation biology suggest that the philosophy of biology will remain an exciting field of enquiry for the foreseeable future.