This paper explores the potential of observational sketching as a social science research tool, informed by our own recent experiments with observational sketching techniques and approaches. We first outline the historical roots of academic sketching and note a recent resurgence of interest in sketching in certain disciplines. We then introduce our own explorations in sketching as method, based on a year-long collaboration between an observational artist and a group of qualitative researchers with interests in creative methods. The paper outlines some of the lessons we learnt from our partnership, focusing on three themes: (i) 'sketchiness'; (ii) 'concentrated seeing' and (iii) sketching as interaction. We conclude that observational sketching generates a refreshingly different form of visual data which has considerable potential to be used as a complement to other methods, including as a participatory method and as a useful tool for thinking. [This article was co-authored by The Morgan Centre Sketchers.]