Safety and organization of a construction site were improved with the application of safety leading indicators and a 5S assessment tool on a project managed using Lean principles. This paper is a report on a project built for a medical device company that manufactures stents and catheters. The $14,000,000 project included two high-tech ISO 8 clean rooms and associated laboratories. Safety related data collected on safety walks on a daily basis was organized for each specialty contractor and normalized for worker hours. This data helped the project focus on areas and trade partners of greatest exposure. The result on the second phase of the project showed significant improvements. The implementation of the 5-S assessment rated the site organization from zero to five for each contractor by a variety of key stakeholders. The results of the 5-S program clustered at the low end at the beginning of the project and significantly improved over time and reached almost 5 as the project approached completion. The paper will reflect on related conceptual foundations and propose follow up investigations aimed at exploring leading indicators and other assessment tools related to safety and quality of work.