The recent trend towards practice-based routes to knowledge has raised methodological questions concerning how best to research practices. Within the geography of art, the expansion over recent decades of collaborative and practice-based approaches has raised similar questions, along with concerns regarding the appropriateness of geographers not trained in art to undertake their own artistic practice within their research. This article grapples with these questions in relation to my own geographic–artistic research, through which I sought to generate boundary understanding or ‘knowing between’ different practices. I outline my own research method, which employed both qualitative interviews and practice-based research with artists, and present two case studies to highlight particular insights gained during the practice-based research, over and above those acquired through semi-structured interviews. These case studies reveal the insubstantial and fragile nature of boundaries between practices and levels of proficiency, and raise political issues for inter-disciplinary activities, problematizing in particular the role of the qualitative interview as a stand-alone method in research into practices, and recent calls for arts-based research only to be conducted by those proficient in art.