What is the relationship between medium and genre in learning and development? North American genre theory suggests following Miller (1984, 1994) that genre is social action. Genres evoke expectations, direct attention, guide action and suggest ‘what motives we may have.’ Yet the relationship between media and genres, as Miller suggested at SIGET IV (1997), is complex. The blog, for example, quickly evolved from being one genre to many genres and, today, might be said to be a medium more than a genre. Bazerman at SIGET IV (2007) argued, following Vygotsky (1997), that genres −particularly written genres− ‘provide highly differentiated, scaffolded communicative spaces in which we learn the cognitive practices of specialized domains.’ This paper provides some evidence for Bazerman’s theory from a case study of students in engineering. It shows how genres may scaffold development by directing attention and focusing motivation to ensembles of genres in a range of media, and repay greater study.