Active learning environments are ideal settings to help students develop process skills such as teamwork, critical thinking, and problem solving. However, implementing active learning pedagogies where students have the opportunity to develop these skills can be challenging in large enrollment courses. With the assistance of undergraduate teaching assistants (TAs), instructors can provide an active learning experience to a large team of students during a typical "lecture" period. Most undergraduate TAs have little to no experience with facilitating active learning environments, and even less with identifying and assessing process skills. Therefore, it is important to provide training for TAs to be effective facilitators in the active learning classroom and to help students develop their process skills. Using an iterative design process, several successful strategies have been developed to help prepare undergraduate TAs to identify, assess, and provide feedback on the development of process skills in active learning classrooms. TAs report that this training was instrumental in improving their communication skills and recognizing process skills.