Abnormalities of psychophysiological arousal and orienting are thought to predispose to schizophrenia, but there have been no prior studies of early psychophysiological functioning in "persistent schizotypals" who remain stably schizotypal across time. This study assessed skin conductance (SC) arousal and orienting at ages 3 and 11 years, electroencephalography (EEG) at age 11 years, and behavior problems at age 17 years in 52 individuals who were stably schizotypal from ages 17 to 23 years, and 104 normal controls. Schizotypy was assessed at age 17 with the Schizophrenism scale, and at age 23 with the Schizotypal Personality Questionnaire (SPQ). Schizotypals had significantly increased SC arousal and increased SC amplitudes to neutral and aversive stimuli at both ages 3 and 11, and also reduced slow-wave left hemisphere EEG power at the beginning of the Continuous Performance Task (CPT) at age 11. Group differences in SC were greater for aversive than neutral stimuli. Schizotypals also had higher age 17 behavior ratings on psychotic behavior, anxiety-withdrawal, and conduct disorder. Findings indicate that heightened SC arousal and orienting in early childhood is a significant risk factor for later schizotypal personality, support a left hemisphere overactivation hypothesis of schizotypy, and illustrate the potential value of a longitudinal definition of persistent schizotypy.