Current trends in service design research include case studies and similar approaches that aspire to reveal what the practice of service design looks like. The understanding of how service design is performed can serve as a base for future research into more specific research endeavours. One area where knowledge is said to be lacking is service prototyping, part of which knowledge this paper attempts to contribute. The main data source for the paper is findings from in-depth interviews with six practicing service designers from some of the more well-known design agencies. The informants consider service prototyping to be a very important part of their work that allows them to learn and communicate about design ideas. The practitioners’ account of how they work with prototypes indicates that service prototyping has different meanings and that the practice of prototyping is very diverse. The interviews also uncover a number of areas that, according to the designers, might prove extra challenging for service prototyping to be successful. This research shows that there is much potential in the not yet fully formed practice of service prototyping.