In a world of growing environmental concern, financial markets are increasingly investing their capital in the transition towards a more sustainable economy. Government initiatives, such as the 2019 European Green Deal, support this shift by aiming to further steer capital flows in this direction. This thesis explored what motivational factors drive the integration of environmental, social, and governance (ESG) concerns in private equity firms which implement a buyout strategy and operate in Sweden. Additionally, this thesis sought to highlight what influence the regulatory environment has on this integration. The data was collected by interviewing representatives from seven private equityfirms and utilising a secondary data analysis of their company reports. The results showed a high degree of sustainability integration in the private equity industry. The analysis further revealed that while intrinsic motivators, predominantly emerging from partners' beliefs, are the primary drivers for some private equity firms, the majority are influenced by extrinsic motivators, with investor demand being the predominant factor. Additionally, we could identify the emergence of industry standards through governmental and non-governmental frameworks. From a practical standpoint, the thesis highlights the necessity of integrating sustainability to maintain legitimacy in the market and secure continuous funding.