The purpose of this thesis is to investigate what barriers and drivers influences the internationalization of private Swedish cleantech firms. The model of a multiple case study was chosen together with a qualitative method and an abductive approach. This was done by acquiring primary information from seven private cleantech companies, all located in Sweden and active in international markets. Furthermore, the theoretical framework presented the Uppsala model, network perspective, international new ventures, born globals, transaction cost theory and the OLI-model. With this theoretical framework, a conceptual model was created which shows how the parts are connected. In the empirical chapter, the primary data is presented to visualize what each individual company said regarding the different constructs of internationalization, drivers, barriers and internationalization decisions. Moreover, the analysis chapter visualizes the similarities and the dissimilarities between the theory and the empirical findings. The thesis concludes that there are both general, as well as specific barriers and drivers that are influential in the internationalization process of private Swedish cleantech firms. These are shown to influence the internationalization decision of managers to take an incremental approach to internationalization. The authors of the thesis also present the view that Swedish cleantech companies are generally too small, lack the financial resources and managerial drive needed to internationalize. The authors also present the theoretical and practical implications and provide recommendations for future research.