Software services are becoming more and more important and intertwined with our daily activities. With the growing complexity of software services and their unpredictably increasing workload, the scalability of these services becomes more and more critical. A scalable service’s implementation can sustain increasing work or load by consuming more hardware resources, as well as releasing hardware resources with decreasing work or load, all while fulfilling its SLAs. The focus of this workshop is on service scalability: the mapping between a service’s work and load and its resulting resource consumption. Even more than performance, scalability is deeply rooted in the service’s architecture and high-level design. In this workshop, we will look at software service scalability from different angles. Scalability is relevant in conventional architectures but even more in cloud computing. Both modelling and analyses of scalability or its related properties like elasticity or efficiency as well as measurements to quantify scalability, elasticity or efficiency are relevant topics for the workshop. Hot Topics in Cloud services Scalability provides a platform for academics and industrial practitioners to exchange novel research ideas and current problems from practice and to identify new and "hot" topics in the field of software service scalability. As indicated by the co-location with ICPE, we are particularly interested in work tackling performance- or scalability-related problems (understood in a very broad sense), but other work related to the creation and management of scalable service-based cloud applications (e.g., from an economic perspective) are equally welcome.