The term ‘conceptual designing’ refers to an activity that various practitioners already undertake, but for which we lack a clear definition. This article provides that definition and uses an example of a design concept called ‘Manhattan’ to present how exactly this type of process happens. We define conceptual designing as a constructive framing and re-framing activity, which is mediated by and targeted at the creation of new design concepts. Conceptual designing as an approach is valuable for addressing the fuzziness and ambiguity typical of research that explores novel areas with new partners, methods and resources. It is by no means a new phenomenon, and the main contribution of the article is the clarification of conceptual designing as a particular approach to designing and researching. The approach embraces openness, resource-construction and collaboration. We conclude that conceptual designing can be especially useful in research and design projects that bring different kinds of people, organizations, technologies and domains together into the forming of new well-founded proposals for development. The presentation of conceptual designing in this paper is written with an intention to provide designers and researchers with terminology and concepts that they may use to structure their work as well as to become more resourceful in reflecting upon their projects. c The Author 2015.