Clinical Information Systems (CIS) have emerged as a new critical infrastructure that influence affordability and security of health care delivery. Complex and conflicting societal requirements, such as providing control for patients over their personal health information and requiring health organizations to assure the security and privacy of patient-specific information, create significant technical challenges for the design of CIS. This paper presents a novel approach that is based on the principles and tools of Model Integrated Computing (MIC), Platform-Based Design (PBD) and Service-Oriented Architectures (SOA). We present a domain-specific, graphical design environment and show how formal system specifications can be mapped to different Service-Oriented Architecture execution platforms through a set of standard languages, such as WSBPEL and XACML. The Model-Integrated Clinical Information Systems (MICIS) design environment includes a suite of domain-specific modeling languages capturing essential aspects of CIS design, model transformation tools that map the domain models onto the standard specification languages of SOA platforms and static model analysis tools checking the consistency and wellformedeness of the multiple-view models. The MICIS design tool is tested in modeling the MyHealth@Vanderbilt patient portal of the Vanderbilt University Medical Center.