Negative symptoms, such as blunted facial affect, are core features of psychotic disorders that predict poor functional outcome. However, it is unknown whether these impairments occur prior to the onset of psychosis. Understanding this phenomenon in the psychosis risk period has significant relevance for elucidating pathogenic processes, as well as potential for informing a viable new behavioral marker for broader social dysfunction and clinical course. The current study sought to determine the nature of facial expression deficits among individuals at clinical high-risk (CHR) for developing psychosis using a comprehensive approach, incorporating clinical interview ratings and automated facial expression coding analysis. A total of 42 CHR and 42 control participants completed clinical interviews and digitally taped segments were submitted into an automated, computerized tool to assess for 7 facial expressions (joy, anger, surprise, fear, contempt, disgust, sadness). Furthermore, relationships between facial expressions and social functioning and available scores on a psychosis conversion risk calculator from a total of 78 participants (39 CHR and 39 controls) were examined. Relationships between measures were also investigated (data was available for the Prodromal Inventory of Negative Symptoms among 33 CHR and 25 controls). Findings from clinical interview indicated that the CHR group exhibited elevated blunting. Furthermore, automated analyses showed that the CHR group displayed blunting in expressions of joy but surprisingly, increased anger facial expressions. Lastly, irregularities in facial expressions were related to decreased social functioning and increased psychosis conversion risk calculator scores, signaling heightened likelihood of conversion to psychosis. These findings suggest that alterations in facial expressivity occur early in the pathogenesis of psychosis and provide evidence for the efficacy of higher resolution measures of facial expressivity in psychosis research. (PsycINFO Database Record (c) 2019 APA, all rights reserved).