Can we make wise policy decisions about still‐emerging technologies—decisions that are grounded in facts yet anticipate unknowns and promote the public's preferences and values? There is a widespread feeling that we should try. There also seems to be widespread agreement that the central element in wise decisions is the assessment of benefits and costs, understood as a process that consists, at least in part, in measuring, tallying, and comparing how different outcomes would affect the public interest. But how benefits and (...) costs are best weighed when making decisions about whether to move forward with an emerging technology is not clear. Many commentators feel that the weighing is often inadequate or inappropriate. Those who argue for a “precautionary” approach to the weighing do so precisely because they feel the need for a restraint on the dominant decision‐making tools and processes for assessing outcomes.This Hastings Center special report examines those tools and processes, taking the method known as cost‐benefit analysis as a starting point. In U.S. governance, CBA, sometimes informed by risk assessment, is the most widely used and extensively studied method, and authoritative reports on genetic and reproductive technologies often use language suggestive of cost‐benefit analysis. There is also a long‐running debate about the role of values in CBA and other formal impact assessment mechanisms—and about how those mechanisms compare to the precautionary principle. The guiding idea in the report is to engage in a close examination of the strengths and limits of CBA for ensuring that emerging technologies are used in ways that square with the public's values, drawing on applications of synthetic biology to illustrate and sharpen the analysis and then considering corrections to CBA and some alternative methodologies that handle values differently. (shrink)