This article reflects on the methodological capacity of the field of knowledge and expertise called spatial design in pursuing spatial quality. The aim is to analyse the methodological aspects of the field and its heuristic processes understood as research-by-design. Research-by-design has an encompassing attention to space through two related and complementary vocations: interpretation and transformation of our environment. The article argues that a research-by-design process is characterized by creative-abductive reasoning. Abduction fits the analytical logic of pragmatism, which is understood as a social philosophy of collective action and knowledge-building. Because of its focus on co-production and social learning, and its use of abductive reasoning, research-by-design offers a powerful inter- and transdisciplinary methodology for exploring transformative capacities and achieving spatial quality, the article argues.