Determining the long-term psychosis-related outcomes of late-teen individuals characterized initially by a nonpsychotic, schizotypic feature (elevated perceptual aberrations) can further our understanding of the developmental pathways leading to schizophrenia, nonaffective psychotic conditions, and psychotic symptoms later in adulthood. Using the well-known laboratory/psychometric high-risk approach, the present study investigated the associations between nonpsychotic perceptual aberrations measured at age 18, in individuals with no prior history of psychosis, and clinical psychotic symptom outcomes 17 years later in midlife (middle 30s). Clinical assessments for hallucinations and delusions were completed for 191 adults (95% of the original sample) in the follow-up study. Elevated perceptual aberrations at age 18 predicted increased levels of hallucinations, delusions, and total psychotic symptoms in midlife as well as psychotic illness. The associations between baseline perceptual aberrations and later psychotic symptoms were not accounted for by general nonspecific psychopathology factors such as anxiety or depression present at age 18. Early detection of subtle, nonpsychotic forms of perceptual disturbance may aid in identifying individuals at increased risk for nonaffective psychosis outcomes in adulthood. Perceptual aberrations may constitute a useful endophenotype for genetic, neurobiological, and cognitive neuroscience investigations of schizophrenia liability.