Managing and containing runaway IT costs for solution deployment is one of the top priorities for enterprises. Cloud Computing, with its on-demand provisioning capability on shared resources, has emerged as a new paradigm for reducing IT costs. In this paper, we describe a solution-based provisioning mechanism to automate the deployment of complex application services on a Cloud infrastructure. We introduce the concept of Composite Appliance and show how it can be used to deploy a complete solution and to simplify management tasks. We illustrate the advantages of our approach with a prototype solution consisting of two-tier application services that are deployed and configured automatically on virtual machine instances without manual intervention.