Research context Open government data (OGD) publication and use is an important feature of an open government. However, In Dutch municipalities, the presumed created value from municipal OGD fails to live up to its potential, despite various OGD initiatives. Furthermore, there is a lack of knowledge about how value creating mechanisms work and how they can be stimulated in municipal contexts. The objective of this study is therefore to identify value drivers and inhibitors in municipal open government data ecosystems. In order to do so, an in-depth analysis is conducted into the stakeholder perceptions regarding values, barriers and success factors related to these systems. Research approach In order to find an answer to the central research question how can the creation of value in municipal open government data ecosystems be facilitated? the ecosystem is approached using actor and strategy models (ASM). This methodology allows in-depth analyses of the stakeholder perceptions throughout the entire ecosystem, and in doing so opens up what is known in ASM as ”the actor dimension” in policy making. By applying the ASM method to open government data ecosystems, this thesis argues for a re-evaluation of the actor dimension in policy making decisions. Furthermore, this thesis seeks to contribute to current OGD theorizations by showing how an in-depth analysis of stakeholder perceptions throughout open data ecosystems not only strengthens policy making decisions down the line, but also expands various forms of value creation through OGD publication and usage. Findings The research question is divided into four sub-questions. The first question is: what does the municipal OGD ecosystem look like? Using a systematic literature review a conceptual model is developed of a municipal open government data ecosystem, portrayed as an actor arena, which is central in an ASM-approach. The ASM- approach allows an assessment of social/political, operational/tactical, and economic value creation. The actors in this model are municipalities, infomediaries, and citizens, who interact by performing tasks, which leads to value creation. Value creation is thus not inherent in specific groups of actors, but created in interactions and dispersed outside the OGD ecosystem itself throughout society. Furthermore, a distinction is made between active and passive interaction executed by citizens. This allows identification of four ecosystem categories: in the administrative domain (1) citizen informing and (2) citizen sourcing; and in the political domain (3) transparency/accountability and (4) collaborative democracy. Lastly, an overview of seven categories of barriers and success factors is presented. This conceptual model was evaluated in an expert review, which led to the second sub-question: to what extent is the conceptual model of the municipal OGD ecosystem accurate, insightful and useful?. The conceptual model was perceived as too data-central, which led to the addition of a societal incentive in the ecosystem as a starting point. Secondly, the distinction between active and passive citizens tasks was perceived as novel insight, which underscored the importance of this viewpoint. Thirdly, the policy context was lacking in the experts’ view, hence it was taken into account by the identified success factors, which included policies. Subsequently, the conceptual model was examined empirically in two case studies concerning a citizen inform- ing OGD initiative and a citizen sourcing OGD initiative. Stakeholder perceptions of infomediaries, municipalities and citizens were measured in order to answer the third sub-question: what are stakeholder perceptions on values, barriers and success factors of data initiatives in municipal OGD ecosystems? This led to several insights. 1.Stakeholders tend to perceive social/political and operational/tactical value of municipalities partaking in OGD initiatives more than economic value. In open government data initiatives for administrative purposes that consist of active citizen interaction mechanisms, additional value is created. This is the case because this research has shown that in such initiatives citizen sourcing benefits account for additional operational/tactical value and responsive governance benefits account for additional social/political value. 2. Infomediaries that were categorized as typical technical initiators of OGD initiatives tend to seek institu- tional support from municipalities or supra-municipal governmental organizations to implement OGD initiatives. Infomediary initiation is effective to ensure a societal incentive for these initiatives. 3. Municipal motives for participating in initiatives were assessed. Whereas some municipalities enthusias- tically participate, others are less willing to do so when OGD initiatives do not fit their perceived institutional contexts. This is especially the case if cross-municipal data-standards are embedded in municipal procedures that do not add value for that municipality. Sometimes municipalities expect infomediaries to generate data technically and are therefore, sometimes municipalities are less dedicated to perform their ecosystem tasks. 4. This research has shown that citizens need to be made aware of their interests in open government data initiatives, and actively encouraged in order for value to be created. The results of the three analyses (literature, expert review, and case studies) insist on a revision of the conceptual model of the municipal ecosystem and generate answers to a fourth sub-question: what factors need to be incorporated in the model in order to increase the creation of value? Four value drivers have therefore been added: (1) institutional support for infomediary initiation, (2) technical support for implementation, (3) reaching out to citizens by engaging re-use platforms, and (4) mobilization of citizens by user-friendliness in OGD applications. Policy recommendations have been formulated to infomediaries, municipalities, and supra-municipal governmental organizations related to coordination and encouragement of value creation in OGD initiatives. Scientific contributions This study contributes to the open government data literature by identifying factors that stimulate value creation in the municipal OGD ecosystem (value drivers) and factors that reduce value generation in this ecosystem (value inhibitors). In contrast to many studies throughout open data literature, this study obtained in-depth insight into the actor dimension underlying municipal OGD ecosystem interactions and revealed some of the structuring mechanisms that influence OGD value creation. Moreover, tasks related to value creation in citizen centered open government data initiatives have not only been made explicit but are specifically attributed to various stakeholders. This study is among the first to apply an ASM approach to open data research, and its findings suggest ASM can be a fruitful method for analyzing open data ecosystems. Societal contributions Value creation in municipal OGD ecosystems should be encouraged by considering the suggested policy recom- mendations for infomediaries, municipalities and supra-municipal governmental organizations. Additionally, the conceptual model of municipal OGD ecosystems developed in this thesis can potentially be used in order to design more valuable OGD initiatives. Future research In future research, additional case studies of OGD initiatives are advised to use an ASM-approach in order to better take stakeholder perceptions into account. Future research should also consider examining OGD initiatives with a more economic focus, as well as those initiated by other categories of infomediaries such as media organizations or academic institutions. Lastly, citizen perspectives could be further evaluated using surveys and this aggregated citizen perspective could then be integrated into the ASM-model.