This paper describes the results of Recommendation 14 of the Integrated Nuclear Materials Management Plan (INMMP) which was the product of a management initiative at the highest levels of the Department of Energy responding to a congressional directive to accelerate the work of achieving integration and cutting long-term costs associated with the management of nuclear materials, with the principal focus on excess materials. The INMMP provided direction to 'Develop policy-level decision support tools to support long-term planning and decision making.' To accomplish this goal a team from the Savannah River Site, Sandia National Laboratories, Idaho National Engineering and Environmental Laboratory (INEEL), and the U.S. Department of Energy experienced in the decision-making process developed a Guidebook to Decision-Making Methods. The goal of the team organized to implement Recommendation 14 was to instill transparency, consistency, rigor, and discipline in the DOE decision process. The guidebook introduces a process and a selection of proven methods for disciplined decision-making so that the results are clearer, more transparent, and easier for reviewers to understand and accept. It was written to set a standard for a consistent decision process.