When deciding about guilt, mock jurors apparently rely on other available evidence. Prior studies by Goodman and those of the present authors both produced this result. Goodman used simulations in which the witnesses were either 6, 10, or 30 years old. In the authors' study, college students watched a 50-minute videotape of a simulated court trial, based on an actual court transcript of a case involving cocaine found in the defendant's apartment. The videotapes were identical except for the age of the eyewitness, which was either an 8-year-old, a 21-year-old, or a 74-year-old male. The 8-year-old and the 74-year-old received more positive ratings than the 21-year-old, suggesting that the child appeared much more competent than expected for his age. However, the jurors did not weigh the child's testimony heavily in determining guilt. Further analysis also showed that jurors used different factors in assessing the credibility of the witnesses of different ages. Research recommendations and 34 references.