Standard 9 of the "National Science Teachers Association Standards for Science Teacher Preparation" is designed to ensure that science teacher preparation programs provide preservice science teachers with the knowledge and skills to understand and successfully engage students in a safe and ethical manner. This standard contains four components describing science teachers' legal and ethical responsibilities, appropriate use of instructional materials (chemicals in particular), emergency procedures and safety equipment, and guidelines for proper use of living organisms in the classroom. In this article, we describe the requirements of Standard 9 and provide guidance on assessments that can be used to present evidence for preservice teachers' competence in each of the four components.