This paper presents a new framework to help assessing the success and its drivers of biomass energy projects. Empirical validation of the framework using data collected from operating grid-connected biomass energy plants in Thailand indicates that competencies of developer and project team members in designing biomass energy plants and conducting environment impact assessment (EIA) are significant factors for the success of the project development phase. In the construction phase, effective coordination, consultation and communication among the project team and the contractors emerge as the most significant success factors, while a competent management and O&M team is found critical to success during the operation phase. External factors such as the presence of supportive legislative, political and regulatory framework are found most instrumental for achieving overall project success. The framework demonstrates the dynamic linkage of project management success in successive lifecycle stages and phases, and thus can be used to evaluate and forecast the likelihood of success of biomass energy projects progressively over their lifecycle. (C) 2009 Elsevier Ltd. All rights reserved.