[en] Research focusing on the practices surrounding screening in Impact Assessment (IA) is limited. Yet, it has been found that development proposals sometimes are adjusted through an informal dialog with IA practitioners prior to or during screening. Such practice is often referred to as ‘grey IA’ in Denmark. This article explores the prevalence, influence and applied rationale of grey IA. Through a questionnaire, data was collected from 121 IA practitioners working within the fields of environmental impact assessment and strategic environmental assessment. It was found that grey IA is a common practice, which influences the outcomes of formal screening procedures through consideration of impacts on neighbours and spatial zones of protection. Grey IA is to some extent motivated by the opportunity to save the resources required for full-scale IA, but an additional ‘green’ rationale also exists. Grey IA may influence the effectiveness of IA systems, but further research is needed before any conclusions can be made. - Highlights: • Screening procedures may function as an informal, ‘grey’ assessment. • Grey assessment is common and influences formal screening outcomes. • Grey assessment is motivated by an opportunity to cut IA costs. • Yet, an environmental, ‘green’ rationale for grey assessment also exists.