This article reports the development and psychometric properties of the 12-item Encouragement Character Strength Scale (ECSS), a measure of the character strength of encouragement using diverse samples (e.g., noncollege adults, Latinx-majority college students, and psychotherapists). The encouragement character strength is the enjoyment and perceived ability to express affirmations to motivate others. This character strength is relevant to counseling psychology because of the latter's historical embrace of human strengths and encouragement's importance in many counseling psychology applications, such as psychotherapy and supervision. Bifactor modeling provided evidence for a general factor and for measurement invariance across race and gender. Ancillary bifactor indices suggest that ECSS should be treated as a unidimensional measure. Criterion-related evidence of validity for ECSS was demonstrated through positive correlations with secure attachment, generativity, empathy, kindness, optimism, social connectedness, the personality traits of agreeableness and extraversion, psychological well-being, and a strength-based focus in psychotherapy (for therapists). Discriminant evidence of validity revealed small correlations with impression management and self-deception enhancement. Incremental evidence of validity showed unique, positive correlations with psychological well-being and generativity, after controlling for other variables. Moreover, self-reported ECSS scores were correlated with positive features of written encouragement messages and with other-reported ECSS scores, providing support for heteromethod convergent validity. The authors also found evidence for ECSS's internal consistency and temporal stability. (PsycINFO Database Record (c) 2019 APA, all rights reserved).