Architecting critical systems has gained major importance in commercial, governmental, and industrial sectors. Emerging software applications encompass practicalities that are associated with either the whole system or some of its components. Therefore, effective methods, techniques, and tools for constructing, testing, analyzing, and evaluating the architectures for critical systems are of major importance. Furthermore, these methods, techniques, and tools must address issues of dependability and security, while focusing not only on the development, but also on the deployment and evolution of the architecture. This newly established ISARCS symposium provided an exclusive forum for exchanging views on the theory and practice for architecting critical systems. Such systems are characterized by the perceived severity of consequences that faults or attacks may cause, and architecting them requires appropriate means to assure that they will fulfill their specified services in a dependable and secure manner. The different attributes of dependability and security cannot be considered in isolation for today’s critical systems, as architecting critical systems essentially means finding the right trade-off among these attributes and the various other requirements imposed on the system. This symposium therefore brought together the four communities working on dependability, safety, security, and testing/analysis, each addressing to some extent the architecting of critical systems from their specific perspective. To this end, the symposium united the following three former events: the Workshop on Architecting Dependable Systems (WADS); the Workshop on the Role of Software Architecture for Testing and Analysis (ROSATEA); and the Workshop on Views on Designing Complex Architectures.