his paper analyzes published and archival testimony of participants in the decision to launch the space shuttle Challenger and extracts new lessons from the decision process for engineering training and engineering managers. Examination of interview testimony, published hearings, and tabular data examined by the decision participants at the time of the Challenger launch show not only that analysis of data and reasoning were flawed, but that the flaws are attributable in large measure not to personal or even organizational failings but rather to a professional weakness shared by all participants. The professional weakness pointed to is either curricular or instructional:​ a gap in the education of engineers. Staff engineers and engineering managers arguing for and against the launch, all of whom agreed they had insufficient quantitative data to support an argument against the launch, were unable to frame basic questions of covariation among field variables, and thus unable to see the relevance of routinely gathered field data to the issues they debated before the Challenger launch. Simple analyses of field data available to both Morton-Thiokol and NASA at launch time and months before the Challenger launch are presented to show that the arguments against launching at cold temperatures could have been quantified, but were not quantified, to the point of predicting degrees of component failure beyond those held by decision participants to be safe. The weakness in engineering education, in turn, is taken to be of a pervasive genre:​ An overemphasis in contemporary universities and research centers on specialization and analysis and an underemphasis on synthesis of knowledge across fields. A larger lesson of the accident, then, is that professional narrowness, leading to false diagnosis of cause-effect relations, can he fatal.