A baby safety car seat having, at least when in use, a state in which the baby safety car seat is convertible into a rollable baby seat, the baby safety car seat, at least in the state, comprising: a lower,support portion including a seat lowermost area configured to contact an external surface to which the seat is to be mounted, and defining an imaginary horizontal base plane, and two, right and left, leg attachment areas on respective right and left sides of the lowermost area; an upper, seating portion having a front, head area and a rear, feet area, the head area being spaced from the imaginary horizontal base plane to a distance greater than the feet area; a right and a left pair of front and rear legs (32, 34), the legs of each pair having distal ends associated with wheels (33, 35) and proximal ends articulated to the seat lower portion at the corresponding leg attachment area, each leg being rotatable between a storage position to be taken in a safety car seat mode of the seat, in which the distal end of the leg is disposed above the imaginary horizontal base plane, and an operational position to be taken in a rolling-carrier mode of the seat, in which the distal end of the leg is disposed below the plane;; and a locking arrangement; characterized in that the seat has an intermediate mode, in which a first one of the legs of each pair is in its operational position whilst the second leg of that pair is in its intermediate position, in which the distal end of that leg is disposed below said plane but which is other than the operational position of this leg; and said locking arrangement is configured for at least one of the following: - locking the first leg in its operational position to the support portion whilst allowing the movement of said second leg between its intermediate and operational positions; and - locking the legs (32, 34) of each pair to each other during their movement between their storage position and the operational position of said first leg combined with the intermediate position of the second leg. a lower,support portion including a seat lowermost area configured to contact an external surface to which the seat is to be mounted, and defining an imaginary horizontal base plane, and two, right and left, leg attachment areas on respective right and left sides of the lowermost area; an upper, seating portion having a front, head area and a rear, feet area, the head area being spaced from the imaginary horizontal base plane to a distance greater than the feet area; a right and a left pair of front and rear legs (32, 34), the legs of each pair having distal ends associated with wheels (33, 35) and proximal ends articulated to the seat lower portion at the corresponding leg attachment area, each leg being rotatable between a storage position to be taken in a safety car seat mode of the seat, in which the distal end of the leg is disposed above the imaginary horizontal base plane, and an operational position to be taken in a rolling-carrier mode of the seat, in which the distal end of the leg is disposed below the plane;; and a locking arrangement; characterized in that the seat has an intermediate mode, in which a first one of the legs of each pair is in its operational position whilst the second leg of that pair is in its intermediate position, in which the distal end of that leg is disposed below said plane but which is other than the operational position of this leg; and said locking arrangement is configured for at least one of the following: - locking the first leg in its operational position to the support portion whilst allowing the movement of said second leg between its intermediate and operational positions; and - locking the legs (32, 34) of each pair to each other during their movement between their storage position and the operational position of said first leg combined with the intermediate position of the second leg. - locking the first leg in its operational position to the support portion whilst allowing the movement of said second leg between its intermediate and operational positions; and - locking the legs (32, 34) of each pair to each other during their movement between their storage position and the operational position of said first leg combined with the intermediate position of the second leg.