There is no debate about the fact that eyewitness identifications can be unreliable. False eyewitness identifications resulting in false convictions have been documented by various authors. This book is based primarily on a premise that I proposed in a 1978 article ("Applied Eyewitness Testimony Research: System Variables and Estimator Variables"): a significant proportion of the errors that occur in eyewitness identification can be prevented by the use of proper procedures. There has been an explosion of scientific research in psychology since the mid-1970s on eyewitness testimony and this book is a culmination of that knowledge plus a strong dose of common sense.