Environmental impact assessment (EIA) is an important part of environmental and public health regulations. Increasing demand of electric consumption in Thailand is a major challenge for authorities trying to ensure satisfactory supply. However, the adverse impacts of development projects are powerful public concerns. Preparations of adequate EIA reports contribute to enhancing overall effectiveness of the EIA process. A sample of 3 EIA reports relating to power development projects was examined, to identify problems and to investigate typical strong and weak points of environmental impact statements, for effective implementation of EIA in Thailand. The competent authority has a well formulated environmental legislation and EIA guidelines and uses a listing method as a key quality control instrument for accuracy and veracity of the reports. Comprehensive descriptions of the major issues and the adverse impacts were defined based on the nature of the construction and operation phases, with adequate information to inform on existing attributes and situations appearing in all critiqued samples. The most important lessons are that there was an absence or weakness in: (i) information on baseline conditions and site–specific information (ii) public participation and (iii) communication involvement of all stakeholders. Increased enforcement could be based on strong, well–written law. The establishment of an independent review committee’s regulation, widespread public participation in every step of the EIA process and formulation of a code of conduct for the consultants, are strongly recommended.