This thesis explores perceptions and preferences on regional action in EU-related frameworks among regional actors in Western Sweden. Building upon the literature on Europeanisation and the Fusion approach, three dimensions of Europeanisation are clarified and explored– download, upload and crossload – and together with a set of five variables that constitute the Micro Fusion Framework; a comprehensive analytical tool is developed. The thesis analyses the intense debate among the members of West Sweden that took place from 2011 to 2013 that focused on how to functionally organise the regional office in Brussels in order to meet future challenges. Surprisingly, the members eventually decided to terminate their cooperation and close the jointly owned office in Brussels in spite of the fact that it has been widely regarded as successful and effective. Diverging perceptions and preferences is understood in terms of three positions on regional action; a download-, upload- and a coherent oriented position. Finally, the thesis presents the empirical findings and discusses in relation to three fusion scenarios, infusion, defusion and clustered fusion. In terms of Micro Fusion Framework, the dynamics shaping why West Sweden was finally regarded as a dysfunctional arena for regional action are explained by a shift of attention and action among regional actors in Western Sweden that led to pressure for further institutional adaptation in order to meet the demand of how ‘to get the best out of the EU’. Further, this redefinition of how to handle EU-affairs within the upload-oriented position was accompanied by positive attitudes towards the potential to bypass the state and thereby pursue regional priorities directly in Brussels given the compound nature of the EU. In contrast, those regional actors that are found to be more download-oriented often question the benefits of uploading activities in practice and advocate close relations to the state. A coherent oriented position recognises the importance of activities related to both of the vertical dimensions of Europeanisation. / I avhandlingen studeras regionala aktörers uppfattningar och attityder till regionalt handlande i EU-relaterade frågor. För att hantera EU-frågor etableras ofta regionala representationskontor i Bryssel. Ett av de största och framgångsrikaste regionala kontoren i Bryssel var West Sweden som representerade västsvenska kommuner och regioners intressen i EU. År 2011 inleds en intern diskussion bland dess medlemmar om hur kontoret bör utvecklas för att möta nya utmaningar i en föränderlig omvärld. Diskussionerna är intensiva, och något överraskande beslutar dess medlemmar att lägga ned verksamheten ett par år senare. I avhandlingen analyseras diskussionen utifrån ett europeiseringsperspektiv. Med hjälp av en analysram som definierar tre dimensioner av europeiseringsprocesser identifieras tre olika positioner i diskussionen; en download-, upload- respektive sammanhållen position. Det kan vara frestande att förstå West Swedens nedläggning som ett uttryck för att subnationella aktörer ”drar sig tillbaka” och föredrar aktiviteter inom nationalstatens domäner. Avhandlingen argumenterar för att så är inte fallet. Nedläggningen av West Sweden förstås som en konsekvens av ökade spänningar mellan regionala aktörer som anammar ett download- respektive upload-orienterat förhållningssätt.