An assembly for a drug delivery device, comprising: - a housing having a distal end and a proximal end, - a rotation member adapted and arranged to be rotated in a first rotational direction and in a second rotational direction with respect to the housing in an operational mode of the assembly, - a drive member which is configured to mechanically cooperate with the rotation member such that the drive member follows rotation of the rotation member when the rotation member is rotated in the second rotational direction and such that the rotation member rotates with respect to the drive member when the rotation member is rotated in the first rotational direction, wherein, in the operational mode, the rotation member is coupled to the drive member via a first uni-directional friction clutch mechanism, which permits rotational movement of the rotation member with respect to the drive member when the rotation member rotates in the first rotational direction with respect to the housing and prevents rotational movement of the rotation member with respect to the drive member, when the rotation member rotates in the second rotational direction with respect to the housing, - a piston rod which mechanically cooperates with the drive member, the piston rod being adapted and arranged to be driven in the distal direction with respect to the housing when the drive member is rotated in the second rotational direction, - a stop member, the drive member and the stop member being coupled to one another by a second uni-directional friction clutch mechanism in the operational mode such that rotation of the drive member in the first rotational direction with respect to the stop member is prevented and such that rotational movement of the drive member in the second rotational direction with respect to the stop member is permitted, - a reset member which is adapted and arranged to be axially moved with respect to the housing between an operating position and a reset position, - at least one biasing member which is adapted and arranged to provide a force tending to bring the rotation member and the drive member out of mechanical cooperation in the operational mode, wherein the assembly is switchable from the operational mode into a reset mode, and wherein, for switching from the operational mode into the reset mode, the biasing member is configured to drive a relative axial movement between the drive member and the rotation member such that the rotation member and the drive member are brought out of mechanical cooperation and, in the reset mode, the drive member is rotatable in the first rotational direction with respect to the rotation member, and wherein, when the reset member is in the operating position, the drive member mechanically cooperates with the stop member and the rotation member, and wherein, when the reset member is in the reset position, the drive member is prevented from mechanical cooperation with the stop member and the rotation member, and wherein the drive member is rotatable in the first rotational direction with respect to the housing, wherein the stop member and the reset member are configured to mechanically cooperate with one another such that the stop member follows movement of the reset member towards the reset position, thereby being brought out of mechanical cooperation with the drive member. - a housing having a distal end and a proximal end, - a rotation member adapted and arranged to be rotated in a first rotational direction and in a second rotational direction with respect to the housing in an operational mode of the assembly, - a drive member which is configured to mechanically cooperate with the rotation member such that the drive member follows rotation of the rotation member when the rotation member is rotated in the second rotational direction and such that the rotation member rotates with respect to the drive member when the rotation member is rotated in the first rotational direction, wherein, in the operational mode, the rotation member is coupled to the drive member via a first uni-directional friction clutch mechanism, which permits rotational movement of the rotation member with respect to the drive member when the rotation member rotates in the first rotational direction with respect to the housing and prevents rotational movement of the rotation member with respect to the drive member, when the rotation member rotates in the second rotational direction with respect to the housing, - a piston rod which mechanically cooperates with the drive member, the piston rod being adapted and arranged to be driven in the distal direction with respect to the housing when the drive member is rotated in the second rotational direction, - a stop member, the drive member and the stop member being coupled to one another by a second uni-directional friction clutch mechanism in the operational mode such that rotation of the drive member in the first rotational direction with respect to the stop member is prevented and such that rotational movement of the drive member in the second rotational direction with respect to the stop member is permitted, - a reset member which is adapted and arranged to be axially moved with respect to the housing between an operating position and a reset position, - at least one biasing member which is adapted and arranged to provide a force tending to bring the rotation member and the drive member out of mechanical cooperation in the operational mode,