A roof system (12) for a cabriolet vehicle (10) has a folding top (14) that is movable between a deployed position and a retracted position covered by a folding-top compartment lid (18). A side fin (16) is movable from a use position, in which the side fin (16) forms a rearward elongation of a support pillar (22), into a pivoted-away position, in which the side fin (16) is swiveled away from the folding-top compartment lid (18) about a swivel axis and into a pivoted-in position in which the side fin (16) is below the folding-top compartment lid (18). Movement of the side fin (16) away from the folding-top compartment lid (18) enables the side fin (16) to be positioned closer to or in the range of movement of the folding top (14) and the folding-top compartment lid (18) during movement between the deployed and retracted positions.