This article deals with the challenge of approaching decision-making processes through strategic environmental assessment (SEA). It is argued that the interaction between policy-making and planning in strategic decision-making processes is a neglected reason for problems with applying SEA, as legislation and guidance on SEA primarily approach either the policy or plan level. To substantiate the argument, the extent of interaction is empirically investigated. Four contemporary decision-making processes in the Danish energy sector are mapped as a series of choices. Fundamental changes with considerable environmental impacts are decided these years, often without preceding SEA processes. The mapping shows a profound interaction between policy-making and planning. In this interaction, public consultation, systematic environmental analyses, and transparency on alternatives are primarily related to choices of planning character. The findings lead to a discussion of the existing SEA guidance that is challenged in terms of adequacy of the guidance to approach the interaction.