A pushchair chassis comprising: first and second carrier mountings (3, 3', 3", 3a, 3b) for supporting a first infant carrier (5a, 5b) on the pushchair chassis, each of the carrier mountings comprising: a socket member (15, 15', 15") having a first socket (17, 17', 17") and a second socket (19, 19', 19") therein, both sockets being configured to receive a correspondingly shaped mounting strut of the first infant carrier, wherein the first and second carrier mountings are connected to the pushchair chassis, and said socket members are pivotable between first and second positions such that for each socket member: (i) the first or second socket respectively is locatable in a receiving position in which a longitudinal axis of the respective socket bore is oriented with respect to the pushchair chassis at an angle suitable for receiving the amounting strut of the first infant carrier, and (ii) when the second socket is in its receiving position, said second socket is vertically elevated with respect to the pushchair chassis, as compared to the first socket in its receiving position, such that said second socket supports the first infant carrier at a higher point on the pushchair chassis than the first socket; wherein each of the carrier mountings further comprise a locking mechanism (23, 23") configured to releasably hold the socket member in each of the first and second positions, and to allow pivoting therebetween; characterized in that a push-button (24, 24") is associated with the locking mechanism to enable release thereof, the button being biased towards an engaged position in which the locking mechanism is held in place, thereby preventing pivoting movement of the socket member, until the button is actuated, which disengages the locking mechanism to enable pivoting of the carrier mounting; optional additional carrier mountings (3, 25), for supporting an optional second infant carrier (5a, 5b) on the chassis, are provided either below or above the first and second carrier mountings; wherein pivoting the first and second carrier mountings between the first and second positions provides additional room for the optional second infant carrier, such that the first infant carrier and the optional second infant carrier would be arranged relative to one another such that one carrier would be provided substantially above and offset from the other carrier, with both carriers being centrally aligned with one another with respect to a plane of symmetry of the pushchair chassis. a socket member (15, 15', 15") having a first socket (17, 17', 17") and a second socket (19, 19', 19") therein, both sockets being configured to receive a correspondingly shaped mounting strut of the first infant carrier, wherein the first and second carrier mountings are connected to the pushchair chassis, and said socket members are pivotable between first and second positions such that for each socket member: (i) the first or second socket respectively is locatable in a receiving position in which a longitudinal axis of the respective socket bore is oriented with respect to the pushchair chassis at an angle suitable for receiving the amounting strut of the first infant carrier, and (ii) when the second socket is in its receiving position, said second socket is vertically elevated with respect to the pushchair chassis, as compared to the first socket in its receiving position, such that said second socket supports the first infant carrier at a higher point on the pushchair chassis than the first socket; (i) the first or second socket respectively is locatable in a receiving position in which a longitudinal axis of the respective socket bore is oriented with respect to the pushchair chassis at an angle suitable for receiving the amounting strut of the first infant carrier, and (ii) when the second socket is in its receiving position, said second socket is vertically elevated with respect to the pushchair chassis, as compared to the first socket in its receiving position, such that said second socket supports the first infant carrier at a higher point on the pushchair chassis than the first socket; wherein each of the carrier mountings further comprise a locking mechanism (23, 23") configured to releasably hold the socket member in each of the first and second positions, and to allow pivoting therebetween; characterized in that a push-button (24, 24") is associated with the locking mechanism to enable release thereof, the button being biased towards an engaged position in which the locking mechanism is held in place, thereby preventing pivoting movement of the socket member, until the button is actuated, which disengages the locking mechanism to enable pivoting of the carrier mounting; optional additional carrier mountings (3, 25), for supporting an optional second infant carrier (5a, 5b) on the chassis, are provided either below or above the first and second carrier mountings; wherein pivoting the first and second carrier mountings between the first and second positions provides additional room for the optional second infant carrier, such that the first infant carrier and the optional second infant carrier would be arranged relative to one another such that one carrier would be provided substantially above and offset from the other carrier, with both carriers being centrally aligned with one another with respect to a plane of symmetry of the pushchair chassis.