The Experience Sampling Method (ESM) is a within-day self-assessment technique. Previous applications of ESM in patients with schizophrenia14- 16 have demonstrated the feasibility, validity, and reliability of the method in this population. Subjects were studied in their normal daily living environments. They each received a digital wristwatch and a set of ESM self-assessment forms collated in a booklet for each day. Ten times per day on 6 consecutive days, the watch emitted a signal (beep) at unpredictable moments between 7:30 AM and 10:30 PM. After every signal, subjects were asked to stop their activity and fill out the ESM self-assessment forms previously handed to them, collecting reports of thoughts, current context (activity, persons present, location), appraisals of the current situation, and mood. All self-assessments were rated on 7-point Likert scales.