The World Wide Web has revolutionized our lifestyle, our economies and services within health care. Health care services are no longer provided only at specialist centers and at scheduled hours, but also through online tools that give health care consumers access to medical information, health records, medical counselling and peer support. Such tools and applications are generally available on larger web sites or gateways called health portals. A large majority of online medical information consumers are laypeople (i.e. non experts) who appreciate the possibility to submit their information needs in their own native language. The information retrieval process where information requests from users and retrieved documents/answers are in different languages is called cross-language information retrieval (CLIR). 

Mental health is one of the medical areas where some online applications have been successfully deployed in order to help people by providing in-depth medical information, counseling and advice. Despite the fact that online health portals are considered priority e-health tools for improving mental health, there are no formal knowledge instruments such as knowledge patterns that explicitly support the development of online health portals in the field of psychology/psychotherapy. 

The goal of this research is to produce and evaluate a set of knowledge patterns, for the development and implementation of cross-lingual online health portals aimed at information seekers without medical expertise in the domain of psychology and psychotherapy. The knowledge patterns synthetize results of three research foundations: 1) User studies of portal interaction, based on interviews and observations about how users experience health information online and personalized search 2) Knowledge integration of existing language technology approaches, and 3) Experiments with language technology applications, in the field of cross-lingual information retrieval/question-answering. The target groups of this research are developers, researchers and health care providers, i.e. people who are responsible for mediating medical information on online health portals for users without medical expertise. 

The chosen research framework is design science, i.e. the science that focuses on the study, development and evaluation of artefacts (objects that help people solve a practical problem). Typical examples of artefacts in IT are algorithms, software solutions and databases, but also objects such as processes or knowledge patterns. The developed and evaluated artefact in this research is a set of knowledge patterns for online health portal development. 

The developed artefact contains fourteen knowledge patterns covering the three research foundations. Formative (structured workshops) and summative (online survey) evaluation of the artefact indicate that the knowledge patterns are useful, relevant and adoptable to a large extent, they also provide further directions for development of online mental health portals. Developing portals with multilingual support and tailored interfaces has the potential of helping larger groups of citizens to access relevant medical information.