Teacher preparation programs help teachers build a foundation for entering the teaching profession. However, learning to teach science cannot be achieved in a mere four years—it is a lifelong endeavor. Teachers continue to learn new science content and new teaching strategies throughout their careers. As professionals, they consistently update their knowledge and skills, reflecting upon and improving their practice. Professional development (PD), in all of its forms, is the key to science teacher learning. This month’s column discusses how science teachers can benefit from professional development experiences.