This study investigates the evolution of the graphical representations used to specify information systems in a community of novice designers supported by a shared design memory, adopting the paradigm of distributed cognition. The nature of the relationship between design notations, quality of design and communication is explicated by considering the interplay of actors, representations, design task and an evolving social and cultural context. An account is provided of how meaningful representational features are transmitted and transformed across generations of designers, and combined in a design language that improves design quality and accommodates varied communication needs and interactional constraints. Diffusion and creation of novel representational features start from a process of critical imitation steered by criteria of instrumental utility set by the individual design teams to address both their needs, concerning level of understanding and desired expressiveness of the design, and the socially regulated expectations about what is required in a good design. These tendencies result in an organizational phenomenon according to which the language of the community evolves by incorporating more sophisticated representational modes, i.e. patterns of features that are used in a socially clever way, in particular to reduce the cognitive load involved in interpretation, and to sustain interaction with the instructor during the exam. It is argued that the cognitive fit between the general characteristics of design task and the expressive modalities allowed by the medium used for the design specifications, plus the individual differences between the novice designers are key factors in sustaining the evolution of the language.