Inter-project knowledge transfer is by scholars widely considered to be a crucial source of competitiveness for project-based organizations. Effective knowledge transfer not only brings economic benefits but also enhances firms’ environmental and social sustainability performance. However, to date, limited research has focused on ascertaining the prerequisites for effective knowledge transfer within the SME context. Correspondingly, through single-case study, this study aims to understand how interrelated organizational factors impact inter-project knowledge transfer in project-based SMEs. Aspects that were found to impact knowledge transfer could be grouped into three dimensions of organizational factors; project characteristics, organizational structure, and organizational culture. More specifically, project similarities, project complexity, horizontal differentiation, and strong interpersonal relationships were found to facilitate knowledge transfer. On the other hand, urgency, absence of formal project managers, low degree of formalization, centralization, low degree of vertical differentiation, and sense of ownership of knowledge were factors identified to hinder knowledge transfer. Furthermore, the present study discovered how the dimensions of organizational factors are interrelated in their impact on inter-project knowledge transfer. Based on the findings, academic and practical implications, and future research avenues are proposed.