Many scientists and doctors hope that affordable genome sequencing will lead to more personalized medical care and improve public health in ways that will benefit children, families, and society more broadly. One hope in particular is that all newborns could be sequenced at birth, thereby setting the stage for a lifetime of medical care and self‐directed preventive actions tailored to each child's genome. Indeed, commentators often suggest that universal genome sequencing is inevitable. Such optimism can come with the presumption that (...) discussing the potential limits, cost, and downsides of widespread application of genomic technologies is pointless, excessively pessimistic, or overly cautious. We disagree. Given the pragmatic challenges associated with determining what sequencing data mean for the health of individuals, the economic costs associated with interpreting and acting on such data, and the psychosocial costs of predicting one's own or one's child's future life plans based on uncertain testing results, we think this hope and optimism deserve to be tempered.In the analysis that follows, we distinguish between two reasons for using sequencing: to diagnose individual infants who have been identified as sick and to screen populations of infants who appear to be healthy. We also distinguish among three contexts in which sequencing for either diagnosis or screening could be deployed: in clinical medicine, in public health programs, and as a direct‐to‐consumer service. Each of these contexts comes with different professional norms, policy considerations, and public expectations. Finally, we distinguish between two main types of genome sequencing: targeted sequencing, where only specific genes are sequenced or analyzed, and whole‐exome or whole‐genome sequencing, where all the DNA or all the coding segments of all genes are sequenced and analyzed.In a symptomatic newborn, targeted or genome‐wide sequencing can help guide other tests for diagnosis or for specific treatment that is urgently needed. Clinicians use the infant's symptoms (or phenotype) to interrogate the sequencing data. These same complexities and uncertainties, however, limit the usefulness of genome‐wide sequencing as a population screening tool. While we recognize considerable benefit in using targeted sequencing to screen for or detect specific conditions that meet the criteria for inclusion in newborn screening panels, use of genome‐wide sequencing as a sole screening tool for newborns is at best premature. We conclude that sequencing technology can be beneficially used in newborns when that use is nuanced and attentive to context. (shrink)