Pervasive Information Systems (PIS) constitute an emerging class of Information Systems where Information Technology is gradually embedded in the physical environment, capable of accommodating user needs and wants when desired. PIS differ from Desktop Information Systems (DIS) in that they encompass a complex, dynamic environment composed of multiple artefacts instead of Personal Computers only, capable of perceiving contextual information instead of simple user input, and supporting mobility instead of stationary services. This paper aims at proposing a design theory for PIS. In particular, we have employed Walls et al. (1992) framework of Information Systems Design Theories (ISDT) to develop a set of prescriptions that guide the design of PIS instances. The design theory addresses both the design product and the design process by specifying four meta- requirements, nine meta-design considerations, and five design method considerations. The design theory has been validated through the implementation of an Information System in the retail context following the theory’s prescriptions. A field experiment revealed that the design theory is capable of leading to valuable and acceptable PIS instances.