This article explores how Environmental Impact Assessments (EIAs) are conducted and their effectiveness in different regions and sectors worldwide. It discusses the quality and control of EIAs, capacity building, and international experiences in Central and Eastern Europe, East Asia, Africa, South and Central America, North America, and the European Union. The article also delves into sector-specific EIAs for policy assessment, land-use plans, waste management, road and rail infrastructure, energy projects, mining projects, and water projects. Key findings include the importance of evaluating EIA systems, the impact of EIAs on transboundary contexts, and the varying approaches to environmental assessments across different regions and sectors.