Background: ERP systems were perceived as the most significant invention for corporations during the rise of information technology in 1990s (Davenport, 1998). Today ERP systems are a multibillion dollar business and used by both LEs and SMEs. Using an ERP system is a continuous project and it is important to constantly look for misalignments in the system and the usage in accordance to the organizational structure also during post-implementation phase (Peng & Nunes, 2017). Problem: Despite the abundance of studies regarding the implementation of ERP systems there is a shortage of studies about the post-implementation phase, where existing post-implementation studies are rather fragmented around a large set of issues (Huang & Yasuda, 2016; Peng & Nunes, 2017). Furthermore, the studies about ERP usage during post-implementation tend to focus on user perspective or evaluation of system or organizational performance (Huang & Yasuda, 2016). Purpose: The purpose of this thesis is to investigate how SMEs improve the usage of ERP systems during the post-implementation phase. Method: To fulfill the purpose of this study, the empirical data was collected through a multiple case study of three cases with SMEs of e-commerce retailer companies in Sweden. Qualitative semi-structured interviews were conducted with top management of the three SMEs in order to get understanding of underlying methods and reasons for the system usage improvement Conclusion: Findings of this study show that SMEs improve their system usage through enhancing knowledge-sharing and organizational learning as well as through unification of the procedures that is achieved through external support and knowledge-sharing.