A shared strategy is a social concept that refers to a type of behavioural pattern that is followed by a significant number of individuals although it is, prima facie, not associated with an obligation or a prohibition. E. Ostrom has argued in favour of the pertinence of social strategies for institutional design and evolution and proposed a characterization suggestive of formal treatment. However, shared strategies as such have not been explicitly used in the context of regulated MAS in spite of their relevance and their affinity to more standard normative notions, of which a rich tradition exists in MAS research. In this paper, we discuss the notion of shared strategy, characterize its distinguishing features, propose its formalization using a temporal epistemic logic, and explore its potential use in regulated multi-agent systems.