The ninth edition of this book will be updated to incorporate the changes in the design provisions of the 2019 American Concrete Institute (ACI) Building Code and Commentary (ACI 318-19). As in previous editions, considerable emphasis is placed on presenting to the student, as well as the practicing engineer, the basic principles of analysis and design of reinforced concrete structures. Each chapter is organized such that the principles of mechanics are presented first to provide a detailed understanding of the theory and observed behavior of reinforced concrete members. This material is then used to describe and to provide the rationale for the design provisions of the ACI Building Code. Numerous examples are presented in each chapter to illustrate the concepts as well as the general approach to design and analysis. The reader may either study in detail the concepts in logical sequence, or merely accept a qualitative explanation and proceed directly to the design process. All example problems will be revised and, as appropriate, new examples will be developed to illustrate the use of available software and design tools currently used in practice.