The validity of self-reported suicide attempt information is undermined by false positives (e.g., incidences without intent to die), or by unreported suicide attempts, referred to as false negatives. In a sample of 1,385 Austrian adults, we explored the occurrence of false positives and false negatives with detailed, probing questions. Removing false positives decreased the rate of suicide attempters from 4.3% to 2.7%. Probing questions also revealed 0.8% false negatives. We recommend using probing questions with both those who report a suicide attempt and those who do not report a suicide attempt to increase the validity of self-reported suicide-related information.