Simon Field integrates business capability modeling into SARM, a formal method for developing and evaluating competing designs for solution architectures. In this article, he shows how this technique can be used to build competing designs for “digital services.” SARM focuses on architecturally significant requirements, as these are most likely to be difficult (and expensive) to change once enshrined in the architecture. The framework uses business capabilities as a way of expressing functional suitability, which introduces a layer of abstraction difficult to achieve through other means.