The widespread, growing interest in the United States in using ultra-high performance concrete (UHPC) in engineered structures is being hindered by a lack of structural design guidance relevant to this class of materials. The material characteristics that form the foundational inputs for existing reinforced concrete design specifications do not represent the behaviors that can be attained with UHPC; therefore, using existing design guidance results in inefficient, overly costly structures. The U.S. Federal Highway Administration has embarked on an effort to develop the needed design guidance for bridges. This document, which will be in the form of a guide specification and will supplement the AASHTO LRFD Bridge Design Specifications, is being coordinated with the relevant subcommittee of the AASHTO Committee on Bridges and Structures. The guide specification will define UHPC, present threshold mechanical and durability properties, define material models, and provide design guidance for flexure, shear, and other critical performance metrics. Both prestressed concrete and mild steel reinforced concrete elements will be covered. This paper discusses the framework for the guide specification and provides insight into key aspects that have been investigated and drafted to date.