Abstract: In today’s business environments, organizations are confronted with rapid technological advancements, regulatory uncertainties, and time-to-market pressures. The ability to detect relevant changes and to react timely and effectively becomes an important determinant for business survival. As a result, companies are striving to adopt agile methods on a larger scale to meet these requirements. The adoption of agile methods at scale poses new challenges such as inter-team coordination and communication, balancing intentional and emergent architecture or coordinating various development activities to produce desirable enterprise-wide effects. The latter can be addressed by applying architecture principles and guidelines. However, there is a lack of academic research on how architecture principles can be created and applied in large-scale agile development. Based on a mixed methods research design, this paper proposes a tool supported collaborative approach for establishing architecture principles and guidelines in an agile fashion.