A mechanism for an office chair, - having a base support which is placeable on a chair column, - having a seat support which is connected to the base support and is movable relative to the base support, - having a backrest support which is connected to both the base support and the seat support and is movable relative to the base support, the pivoting of said backrest support causing the seat support to move relative to the base support, - having a spring arrangement which acts between the backrest support and the seat support for determining the pivoting resistance of the backrest support, wherein the backrest support is pivotable relative to the base support against the spring force of the spring arrangement, wherein the seat support is tiltable relative to the base support against the spring force of the spring arrangement and the spring arrangement also determines the tilting resistance of the seat support, and - having a coupling element which is able to movable connect base support and seat support, wherein the backrest support is pivotably hinged both on a rear end of the seat support, thereby realizing a first seat support pivot axis which extends transversely with respect to the seat longitudinal direction, and on the base support, thereby realizing a first base support pivot axis which extends transversely with respect to the seat longitudinal direction, wherein pivoting the backrest support causes the seat support to move relative to the base support, and wherein the coupling element is pivotally hinged on a front end of the seat support, realizing a second seat support pivot axis which extends transversely with respect to the seat longitudinal direction, and on the base support, realizing a second base support pivot axis which extends transversely with respect to the seat longitudinal direction, characterized in that the spring arrangement acts between the seat support pivot axes (12, 17), wherein the ends (24, 25) of the used spring elements cooperate with the seat support pivot axes (12, 17). - having a base support which is placeable on a chair column, - having a seat support which is connected to the base support and is movable relative to the base support, - having a backrest support which is connected to both the base support and the seat support and is movable relative to the base support, the pivoting of said backrest support causing the seat support to move relative to the base support, - having a spring arrangement which acts between the backrest support and the seat support for determining the pivoting resistance of the backrest support, wherein the backrest support is pivotable relative to the base support against the spring force of the spring arrangement, wherein the seat support is tiltable relative to the base support against the spring force of the spring arrangement and the spring arrangement also determines the tilting resistance of the seat support, and - having a coupling element which is able to movable connect base support and seat support, wherein the backrest support is pivotably hinged both on a rear end of the seat support, thereby realizing a first seat support pivot axis which extends transversely with respect to the seat longitudinal direction, and on the base support, thereby realizing a first base support pivot axis which extends transversely with respect to the seat longitudinal direction, wherein pivoting the backrest support causes the seat support to move relative to the base support, and wherein the coupling element is pivotally hinged on a front end of the seat support, realizing a second seat support pivot axis which extends transversely with respect to the seat longitudinal direction, and on the base support, realizing a second base support pivot axis which extends transversely with respect to the seat longitudinal direction, characterized in that the spring arrangement acts between the seat support pivot axes (12, 17), wherein the ends (24, 25) of the used spring elements cooperate with the seat support pivot axes (12, 17). both on a rear end of the seat support, thereby realizing a first seat support pivot axis which extends transversely with respect to the seat longitudinal direction, and on the base support, thereby realizing a first base support pivot axis which extends transversely with respect to the seat longitudinal direction, on a front end of the seat support, realizing a second seat support pivot axis which extends transversely with respect to the seat longitudinal direction, and on the base support, realizing a second base support pivot axis which extends transversely with respect to the seat longitudinal direction,