  In multiple stellar systems interactions among the companion stars and their
discs affect planet formation. In the circumstellar case tidal truncation makes
protoplanetary discs smaller, fainter and less long-lived than those evolving
in isolation, thereby reducing the amount of material (gas and dust) available
to assemble planetary embryos. On the contrary, in the circumbinary case the
reduced accretion can increase the disc lifetime, with beneficial effects on
planet formation. In this chapter we review the main observational results on
discs in multiple stellar systems and discuss their possible explanations,
focusing on recent numerical simulations, mainly dealing with dust dynamics and
disc evolution. Finally, some open issues and future research directions are
examined.
