Cases in which employees' uses of social media harm their company's reputation highlight the need for a measure to evaluate employees' company reputation-related social media competence (RSMC). Drawing on reputation and human capital theory and data from four occupationally diverse samples of employees, this study develops and validates a new, multidimensional measure of RSMC, or an employee's ability to use social media without causing harm to the employer's reputation. Exploratory factor analyses, first- and second-order confirmatory factor analyses, and structural equation modeling all provide strong evidence of the convergent, discriminant, known-group, and nomological validities of the proposed RSMC scale. The higher-order RSMC construct also relates to job demands and resources and to two behavioral outcomes: bad mouthing and positive word of mouth. The RSMC scale also exhibits test–retest reliability and ecological validity. Thus, the new scale offers both research directions and managerial implications.