The article discusses the importance of developing the theory of Environmental Impact Assessment (EIA) due to its inadequate theoretical basis. It identifies two main interpretations of the role of science in EIA: EIA as applied science and EIA as civic science. Five distinct models are identified within these paradigms, based on existing philosophies of science. The article proposes a broad model for advancing theory in EIA, emphasizing the need to focus on the purposes and outcomes of EIA, rather than just the process and procedure. This shift in research agenda is crucial for EIA to reach its full potential as a globally significant decision-making tool.