Model verification and validation (V&V) are enabling technologies used to quantify the accuracy of results from computational models that inform engineering decisions. Model V&V procedures are needed by government and industry to reduce the time, cost, and risk associated with full-scale testing of products, materials, and complex systems. Quantifying the accuracy of model calculations provides the decision-maker with the information necessary for making high-consequence decisions. The development of guidelines and procedures for conducting model V&V is currently being defined by a broad spectrum of researchers. A group of ASME members from industry, academia and national labs initiated a volunteer effort to merge the uncertainty analysis activities of the experimental and computational communities. The objective was to provide a methodology by which a quantitative assessment could be made about validation of computational software for fluid dynamics and heat transfer. The elements identified as necessary for validation include A) code verification and solution verification, B) effect of input parameter uncertainty on simulation uncertainty, C) uncertainty of an experimental result, and D) a metric by which experimental and simulation uncertainties can be compared. It is important to understand that validation requires both an experiment with its associated uncertainty and a simulation with its associated uncertainty. This presentation will discuss and summarize the use of V&V20-2009 for computational modeling of engineering applications. The standard has been applied to heat transfer and thermal applications for modeling the thermal response of objects embedded in reacting materials, the thermal response of large assemblies in high heat flux and temperature environments from fuel fires, structural response of assemblies in high-speed impact, and the electromagnetic response of assemblies to external fields. The use of V&V20-2009 [1] to these applications is discussed. The lessons learned and insights from the application of the standard are discussed.