Millions of critically ill adults undergo tracheal intubation in an emergency department or intensive care unit each year, nearly 40% of whom experience hypoxemia, hypotension, or cardiac arrest during the procedure. Over the last two decades, a series of randomized trials have evaluated the tools, techniques, devices, and drugs used to perform emergency tracheal intubation to determine which interventions improve outcomes and which are ineffective or harmful. Results of these trials have demonstrated that: preoxygenation with noninvasive ventilation and administration of positive pressure ventilation between induction and laryngoscopy prevent hypoxemia during intubation; video laryngoscopy facilitates successful intubation on the first attempt and may prevent esophageal intubation; use of a stylet is superior to intubation with an endotracheal tube alone and is comparable to use of a bougie; and administration of a fluid bolus before induction does not prevent hypotension. Many additional decisions clinicians face during emergency tracheal intubation are not yet informed by rigorous evidence. Randomized trials must continue to examine systematically each aspect of this common and high-risk procedure to improve patient outcomes and bring forth an era of evidence-based emergency tracheal intubation. This article is open access and distributed under the terms of the Creative Commons Attribution 4.0 International License (https://creativecommons.org/licenses/by/4.0/).