Project Summary/Abstract Cryo-EM and cryo-ET have emerged as indispensable tools to visualize biological structures across a broad range of scales, from small molecules and proteins to entire cells. Despite the growing enthusiasm for these methods, cryo-EM and cryo-ET are relatively inaccessible for several reasons: first, there are inadequate training materials for cryo-EM and cryo-ET novices; second, there is a growing expertise gap between experienced practitioners and newcomers; and third, few institutions have the means to procure and maintain the high cost of instrumentation. In order to address these limitations, we created ‘CryoEM 101’, a self-paced, interactive online course that uses a user-friendly and media-rich approach to engage and teach newcomers on the basics of the typical cryo-EM project workflow. We now propose to expand CryoEM 101 by developing new content that emphasize best practices in sample and grid preparation, creating self-assessment quizzes for users to gauge their learning, and integrating our training material with a broader “merit badge” certification program that is currently under development. We also propose to create CryoET 101, which will be modeled after CryoEM 101 by using video, 3D animation, and interactive modules to teach the principles and best practices underlying cryo-ET. Like CryoEM 101, CryoET 101 will be divided into several chapters, each of which will focus on a distinct step along the cryo-ET workflow and will contain visually engaging modules that teach core principles. The accuracy and quality of the training material will be evaluated by separate Advisory Boards for cryo-EM and cryo-ET that consist of subject experts in each method. User proficiency will be assessed through end-of-chapter and end-of-course quizzes. Overall, the goal of this proposal is to guide cryo- EM and cryo-ET newcomers to a point along their training where they can independently prepare and optimize their specimens for high-quality data collection at dedicated EM centers.