This document introduces the Level of Development (LOD) Specification, which provides detailed definitions and examples of building elements at different LODs to improve communication among users of Building Information Models (BIMs). The LOD Specification expands on the LOD schema developed by AIA to define element geometry and required information at LOD 100-400 and a new LOD 350. It is organized by CSI Uniformat and addresses a variety of building systems. The goal is to reduce risks of miscommunication by clarifying what teams are expected to deliver at each stage of design and construction.