This guidebook demonstrates how a state transportation agency (STA) can improve its project scoping process (PSP) and practices to produce a project cost estimate and schedule that facilitate programming decision making and accountability. It illustrates the effort needed to develop a robust cost estimate and then manage to a baseline budget and scope throughout the project delivery cycle. The guidebook consists of two parts. Part 1, “Research Results about the PSP,” addresses the following issues: why STAs should formalize the PSP; current practices for PSP; and how agencies can implement an effective PSP. Part 2, “Implementation Guidelines,” provides an easy-to-understand layout and describes how to implement the PSP. The guidelines are divided into three sections. Each section details one of the three major activities of the PSP—develop the project, analyze the alternatives and document findings, and develop the recommended alternative. The guidelines also have two appendices. The first appendix summarizes the tools that can be used while performing different activities in the scope development process. The second appendix is the list of online links to various resources and tools to support the PSP, as referenced in this guidebook.