The construction of green buildings differs from that of traditional buildings in terms of the design, materials, and processes. The barriers to the development of green buildings, such as the high cost and project delay, further indicate that the productivity of green building construction needs to be tackled. This study aims to identify the critical factors affecting the productivity of green building construction projects by assessing the likelihood, impact, and criticality of the factors with comparisons against traditional projects. To achieve the objective, 26 factors were identified from a comprehensive literature review and interviews with industry experts. A questionnaire survey was then performed with 32 professionals experienced in green building projects, and three postsurvey interviews were also conducted. The results indicated that workers' experience, technology, design changes, workers' skill level, and planning and sequencing of work were the top five most critical factors affecting the productivity of green building construction projects. Furthermore, the differences in the criticality of the technical factors between green and traditional projects were remarkable, which should draw the practitioners' attention. The findings from this study not only fill a gap in the project management body of knowledge for green buildings but also help practitioners identify specific adjustments to traditional project management processes and practices achieving a more productive delivery of green buildings.