The aim of this workshop is to bring together researchers and practitioners from academia and industry to discuss and advance the state of the art in the development and security of applications utilising Cloud Computing. Cloud computing is an emerging research topic widely discussed within the community of distributed systems and Grid computing experts. It promises to vastly change the implementation, usage and management of computing systems both in the public and private sector. The proposed benefits of the technology would offer reduced overheads by removing procurement and charging by usage, ultimately delivering computing as a utility. An additional feature is the extensibility of clouds; enabling allocated resources to expand and contract dependent upon the requirements for usage. The potential gains lie not only with the efficient allocation of resources, but also a green utilization of resources by maximizing the usage of a resource through the dynamic reallocation of jobs to cloud resources. The adoption of such technology by organisations clearly carries a number of significant benefits to the computing research community, such as dynamic provisioning of data and software to support project tasks. However, there are also a number of associated challenges which must be considered prior to a widespread uptake of Cloud Computing as a major computing architecture. In particular, the legal and technical management of the systems, the data and the services provided need to be investigated. The CAS workshop, therefore aims to connect and allow sharing ideas, problems and solutions between those researchers and practitioners that face Cloud challenges.