The present study provided the first examination of the construct validity of the Multidimensional Schizotypy Scale (MSS) and the first assessment of its psychometric properties outside of its derivation samples. The MSS contains 77 items that assess positive, negative, and disorganized schizotypy. A large multisite sample of 1,430 participants completed the MSS and measures of schizotypal personality traits and the five-factor model of personality. The MSS subscales had good-to-excellent internal consistency reliability that showed no shrinkage relative to the MSS derivation samples. The psychometric properties and intercorrelations of the MSS subscales were closely consistent with the derivation findings. The MSS Positive Schizotypy subscale had a strong association with cognitive–perceptual schizotypal traits (large effect), positive associations with personality traits of neuroticism and openness to experience, and negative associations with agreeableness. The MSS Negative Schizotypy subscale had a strong association with interpersonal schizotypal traits (medium effect) and negative associations with personality traits of extraversion, openness, and agreeableness. The MSS Disorganized Schizotypy subscale had a strong association with disorganized schizotypal traits (medium effect), a positive association with neuroticism, and a negative association with conscientiousness. The findings were consistent with the a priori predictions and support the construct validity of the MSS.