The present study sought to examine a linguistic measure of authenticity by evaluating the language people use when responding to prompts designed to elicit varying amounts of authenticity. Participants (N = 240) wrote an introductory blog post about the self, with instructions to emphasize either authenticity, inauthenticity, or neither (i.e., control condition), and completed three rating items and a self-report measure of trait authenticity. Responses to the prompts were then run through the Linguistic Inquiry and Word Count (LIWC) program for linguistic analysis. The rating items were used to assess the effectiveness of the prompt manipulation and scores on the LIWC authentic category were then compared across prompt condition to determine the validity of this category. Overall, the results indicated that the prompt manipulation was effective and the LIWC authentic category did not demonstrate sufficient evidence of construct validity. Exploratory analyses were then conducted to confirm the underlying composition of the LIWC authentic category and identify linguistic composites that effectively characterize both state and trait authenticity.