 Participation in this study will last up to 5 years. The initial screening visit will be used to determine whether a participant is eligible for the group displaying basic symptoms or the control group. Initial screening will include giving a blood sample for routine lab tests, a physical exam, a drug test, and questions about medical history and symptoms. All participants will then partake in baseline evaluations, which involve assessments concerning concentration, problem solving, memory, social skills, and ability to identify smells. Participants will also respond to questions about symptoms, school and social functioning, stressful situations, and family history of illnesses. The participants who meet the criteria for basic symptoms will attend monthly 1-hour follow-up visits for the first year of the study. During these visits, participants will be asked about the status of their basic symptoms and use of medications. For the second year of the study, follow-up visits will occur every 2 months, and for the third, fourth, and fifth years of the study, visits will be every 3 months. Repeat baseline assessments will occur every 6 months, with each assessment visit lasting about 5 hours. All participants will undergo endpoint evaluations that follow the same format as most baseline assessments. Participants who develop a psychotic disorder during the study will attend an additional follow-up visit 6 months after the endpoint evaluation to confirm diagnosis. Participants who decide that they no longer wish to attend regular study visits may be asked to participate in follow-up telephone interviews about their basic symptoms every 6 months. 