This article reviews existing measures related to evidence-based practices with children and self-efficacy and describes the development and psychometric properties of the Evidence-Based Mental Health Practices With Children Efficacy Scale. This scale was developed to assess students' and clinicians' self-efficacy in their abilities to use evidence-based practices with children. Pre- and posttests were compared for five cohorts of master's of social work students enrolled in a child and adolescent mental health course. Results provide initial support for the psychometric properties of this scale. Exploratory factor analysis results support retaining all items, and internal consistency of the scale was excellent. Results also provide support for criterion-related validity, with knowledge predicting an increase in self-efficacy. Implications and uses of the scale are discussed.