Brief self-report questionnaires that assess attenuated psychosis symptoms have the potential to quickly and effectively screen many people who may benefit from clinical monitoring or early intervention. The current study sought to examine and compare the criterion validities of attenuated symptoms screening tools with diagnoses obtained from the clinician-administered Structured Interview for Psychosis Risk Syndromes (SIPS). Three screening questionnaires (Prime Screen, Prodromal Questionnaire-Brief, and Youth Psychosis At-Risk Questionnaire-Brief) were administered just prior to the SIPS interview in a sample of adolescents and young adults seeking mental health services. Using thresholds recommended by instrument authors as well as empirically derived optimal thresholds, the sensitivity, specificity, positive predictive value, and overall accuracy of each self-report measure with regard to SIPS diagnosis were obtained. Screeners correlated highly with the SIPS and demonstrated equivalent overall efficiency in capturing psychosis risk status. All three screeners appear to be useful and valid assessment tools for attenuated symptoms, with each instrument demonstrating relative benefits. The validation of attenuated symptoms screening tools is an important step toward enabling early, wide-reaching identification of individuals on a course toward psychotic illness.