Among individuals experiencing internalizing psychopathology, high levels of emotion reactivity--the degree to which they experience emotions strongly or intensely, over extended periods of time, and as elicited by a variety of stimuli--increase risk for self-injurious thoughts and behaviors. Researchers developed the Emotion Reactivity Scale (ERS) to assess emotion reactivity, with psychometric support for the measure largely restricted to at-risk clinical populations. We know little of the psychometric properties of the ERS when administered as a screening measure in community assessments. In a study of the psychometric properties of the ERS in a non-clinical assessment of adults, we recruited 105 participants (M[subscript age]=44.6; 82.9% female) as part of a larger study of adolescent social anxiety and family relationships. Participants completed the ERS, self-report measures of various psychosocial domains, and an impromptu speech task, before and during which they self-reported their arousal. Scores taken from the ERS demonstrated strong internal consistency and demonstrated facets of validity: (a) positive relations with measures of internalizing psychopathology and parent-adolescent conflict, and negative relations with a measure of quality of life (convergent validity); (b) relations with self-reported anxiety and safety-seeking behaviors, over-and-above self-reported depressive symptoms (incremental validity); and (c) relation with self-reported state arousal during the impromptu speech task, over-and-above self-reported arousal at baseline (criterion-related validity). These findings support the psychometric properties of the ERS when administered in non-clinic assessments of adults. As such, they have important implications for screening assessments designed to identify adults who display the potential for self-injurious thoughts and behaviors. [This paper was published in "Journal of Psychopathology and Behavioral Assessment" v41 p730-740 2019.]