For the last couple of years, The Hastings Center has been running a research project titled “The Ethical Issues of Synthetic Biology” (funded by the Alfred P. Sloan Foundation) that is focused primarily on whether the prospect of altering microorganisms to meet human ends is intrinsically troubling. “Synthetic biology” is not necessarily limited to the alteration of microorganisms, but the applications now under development—such as yeast that produce a precursor of the antimalarial drug artemisinin or blue-green algae that produce fuel—are certainly limited to that. A set of essays in this issue of the Report features a variety of different takes on the field.