The 170-plus postconviction DNA exonerations of the last 15 years have exposed numerous problems that have contributed to convicting the innocent. The specific problems include eyewitness error and flawed eyewitness procedures, false confessions, forensic error or fraud, police and prosecutor misconduct, inadequate defense counsel, jailhouse snitch testimony, and others. A theme running through almost every case, that touches each of these individual causes, is the problem of tunnel vision. Tunnel vision is a natural human tendency with particularly pernicious effects in the criminal justice system. This Article analyzes tunnel vision at various points in the criminal process, from police investigation through trial, appeal, and postconviction review. The Article examines the causes of tunnel vision in three domains. First, tunnel vision is the product of natural human tendencies - cognitive distortions that make it difficult for human beings in any setting to remain open-minded. Second, institutional or role pressures inherent in the adversary system can exacerbate the natural cognitive biases, and induce actors to pursue a particular suspect too soon or with too much zeal. Finally, in some ways the criminal justice system embraces tunnel vision as a normative matter; it demands or teaches tunnel vision overtly, as a matter of policy or rule. This Article concludes by examining possible corrective measures that might be adopted to mitigate the effects of tunnel vision.