In 2006, a large scale energy infrastructure company (the Company) faced a growing portfolio of capital projects, including several potential mega-projects. The company had a solid history as an operator but did not have in-house cost engineering capability to evaluate and manage such large capital investments. Significant challenges surrounding estimate accuracy provided strong motivation to improve. Fast forward to 2018 and the Company has mature in-house Cost Engineering expertise and an integrated suite of effective cost estimating and modeling, risk analysis, and historical project benchmarking methods and tools that are aligned with AACE® International Recommended Practices. Improvements in estimate accuracy and performance repeatability have been excellent and demonstrable. This case study will walk through the evolution from immature processes and tools, to fully customized, ground-up tools and finally towards the use of standardized industry tools extensively calibrated with integrated systems now used to develop estimates for the multi-billion dollar annual capital spend program. A company acquisition now presents new challenges. A road map for future improvement and integration will also be explored.