A good estimation tool offers a “model” of a project and is usually used to estimate cost and schedule, but it can also be used to help make trade decisions that affect cost and schedule as well as to estimate risks and opportunities. It was evident that Rolls-Royce needed a cost model to underpin decisions when they launched a Software Product Line initiative. The first generation cost model was based on COCOMO II, which represents the software product as a single size measure (Source Lines of Code) but makes limited use of the architecture or any characteristics of the product being developed. The next generation of the cost model, currently under development, is intended to account for the quality attributes of the core assets and the resulting products in order to estimate their impact on cost and net-benefit to the business. The objective of this paper is to describe our current efforts to integrate key quality attributes into the SPL cost model. We describe the quality attributes selected, the reason for their selection and the benefits we expect to obtain after integrating them into the model.