"Physics by Inquiry: An introduction to Physics and the Physical Sciences" is the product of more than 20 years of research and teaching experience. Developed by the Physics Education Group at the University of Washington, these laboratory-based modules have been extensively tested in the classroom. Volumes I and II provide a step-by-step introduction to fundamental concepts and basic scientific reasoning skills essential to the physical sciences. Volume III, currently in preparation, extends this same approach to additional topics in the standard introductory physics course. "Physics by Inquiry" has been successfully used: to prepare preservice and inservice K-12 teachers to teach science as a process of inquiry; to help underprepared students succeed in the mainstream science courses that are the gateway to science-related careers; and, to provide liberal arts students with direct experience in the scientific process, thus establishing a solid foundation for scientific literacy.