The promise of Model-Based Systems Engineering (MBSE) and its advertised benefits hinge on the ability of our profession to integrate engineering disciplines and project management across the system life cycle. In particular, connecting system architecture to the economics of developing such a system is a critically important topic but has not drawn significant attention by the system engi-neering community. Such integration requires two things: (1) the standardization of mul-ti-disciplinary terms and functions, and (2) the establishment of rules that govern relationships be-tween cross-functional models and modeling environments. The contribution of this paper sits squarely in those two areas by (1) establishing common terminology that describes systems engi-neering and cost estimating and (2) proposing specific cost factors and counting rules that can be used to estimate systems engineering effort using the COSYSMO cost model in an MBSE environ-ment. This paper enables the convergence of COSYSMO and MBSE by updating the COSYSMO counting rules to specifically address size driver selection and assignment in a SysML model; demonstrating how advanced queries and cross cutting views provided by modern, MBSE tools increase the completeness, quality and consistency of the parametric cost estimation results, and to reduce the cycle time from architecture to cost estimation. It defines the critical modeling patterns and guidelines for identifying system model content and level of detail for cost estima-tion and provides an approach to connect attributes and properties in a system model to the vari-ables in the COSYSMO cost estimating relationship.