As a result of the deregulation of the Swedish railway market, the differentfunctions involved during the life cycle of railway products have been spreadout over different actors. The trigger for the work presented in this thesis wasthe insight that, since function-specific knowledge of the railway in Swedenbelongs to different organizations, special efforts would be needed to achieve aholistic picture of a railway product during the conceptual design phase. However,there is a lack of methods developed for groups with participants fromdifferent organizations possessing different functional knowledge about a product.The overall aim of the research for this thesis was therefore to develop anideation method and a concept selection method specifically for groups actingin the context of the Swedish deregulated railway market, with members fromdifferent organizations with different functional knowledge. By means of actiondesign research, the methods were developed within the scope of a researchproject involving four different actors on the Swedish railway market.The project group tested Method 635, the gallery method and the SIL method.Overall, the gallery method was most popular and the SIL method leastpopular among the participants. Method 635 was found to have a considerablyhigher idea and concept generation rate than the gallery and SIL methods.The developed ideation method combines the rotational viewing of generatedideas in the group and gallery viewing with steps of verbal interaction wherethe group members take turns to present and comment on generated ideas. Theproject group regarded the developed method as the best method of all themethods which they had tried, and it outperformed the other methods with regardto the total number of generated concepts and ideas. The views of the projectgroup on the method correlated positively to the views of participants takingpart in field tests of the method.The developed concept selection method combines refined versions of theprocedures for topic clarification, goal specification, requirement specificationand concept screening developed by Pahl and Beitz with a concept scoring procedurebased on the life cycle and societal costs associated with each conceptthat fulfils the stated requirements.The most important effect of the composition of the group was found to bethe wide range of viewpoints on the topic at hand that the representative groupof different relevant actors was able to provide.