Lean aims to maximize customer satisfaction while minimizing waste. However, Lean philosophy has not been well understood yet in the construction industry for the fact that the complexity and dynamic nature of construction projects bring up uncertainties that may be hardly handled by construction practitioners. Moreover, project-based nature of construction business makes Lean implementation even more challenging for construction people. Even though Lean efforts in construction have recently increased, there are problems with the implementation processes. It is undeniable that successful Lean implementation strongly affects project performance. Therefore, it is essential to reveal enablers and barriers in Lean implementation so that the construction industry practitioners might conduct projects more effectively and satisfy project requirements (i.e. schedule, budget, safety). This study aims to provide a set of core enablers and barriers of Lean implementation in construction projects and guide construction professionals to better satisfy project requirements. Within this context, the study proposes seven major enabler and barrier groups, namely the financial, managerial, technical, workforce, culture, government, and communication and twenty-seven components for each group. Moreover, a survey was designed and administered to Lean practitioners to rank the enablers and barriers based on importance level. Clear understanding of technical requirements in Lean practices was ranked as the most important enabler of Lean implementation whereas lack of top management support was ranked as the most important barrier in the Lean implementation. However, the average rankings were not found to be diverging indicating that selected components of enabler and barrier groups are properly chosen. The study is expected to lead Lean practitioners with creating value to customers while preventing them from experiencing waste.