The concept of function has a tainted history in science and philosophy, having been mated to teleology and harnessed to pull various discredited theories. This presentation begins with a short history designed to give a sense of what made the concept of function problematic. Current philosophical attention to the problem revolves ellipse-like around two foci: systematic or system relative accounts, and selectionist accounts. These are briefly described, and the systematic account is defended on the grounds that it captures a ubiquitous explanatory strategy in science and engineering, and that selectionist accounts are, in contrast, limited to evolutionary biology (and, perhaps, designed artifacts), and make it difficult to articulate various important issues in evolutionary biology itself.