Enterprise Architecture (EA) is introduced as a general approach to aligning business and IT within an organization. Therefore, EA should guide organizations through the business, information, process, and technology changes necessary to execute their strategies. The developments in the various layers (business architecture, IS architecture and IT architecture) influence each other and, consequently, architectural matters are critical for achieving alignment between the business and its information systems. An essential component of EA is design principles, which strive to manage the complexities in business processes and IT systems. Some scholars argue that design principles are the essence of EA. Design principles can either align, or misalign, IT/IS artefacts with the architecture. If the principles are aligned, they will have a positive impact on the organizational effects and values, but if they are misaligned, they will have a negative impact on effects and values. Unfortunately, EA principles have not yet received much research attention, although there are a few scholars addressing EA principles from a conceptual point of view. Empirical insights regarding the role and usefulness of EA principles in practice are still lacking. The purpose of this empirical study is to describe how various dimensions of alignment are considered by design principles. One crucial design principle will be mainly highlighted, namely the delineation principle. Delineation principles focus on how to delineate IS or business domains and create "systems of systems" that are in harmony with different requirements of the business. A case study of a large Swedish insurance company is used as a basis for the analysis. The result shows that the IS and business delineation principles do not mirror each in regards of the dimension of alignment. The result also shows that design principles mainly consider the functional dimension of alignment. This paper argues that it is essential to evaluate IS and business design principles against each other based on functional, structural, socio-cultural and infological alignment.