Universal screening is increasingly becoming part of prevention and early intervention best practice in schools. Although the number of schools engaging in universal screening has increased over the past decade, emotional and behavioral problems are often their primary focus. Problem-focused screening, however, does not address positive contributions to mental health and is useful for only a small percentage of students. Conversely, the information obtained when assessing for strengths is relevant for all students. The inclusion of a strength-based approach in school-based universal mental health screening serves to broaden educators' understanding of mental health and can inform reactive and proactive interventions that address problems and enhance strengths. This article discusses the knowledge and skills needed to implement universal complete mental health screening, that is, screening that assesses for students' strengths and problems. A detailed description of complete mental health screening is provided, followed by a step-by-step implementation guide with specific considerations for practitioners who wish to engage in complete mental health screening as part of comprehensive efforts to promote the well-being of all students. Finally, the process of complete mental health screening is illustrated with a case example.