System comprising an image forming apparatus for forming an image on a recording material and a process cartridge (PY, PM, PC, PK) detachably mountable to a main assembly of the image forming apparatus, the process cartridge including: a first unit having an image bearing member; a second unit having a developer carrying member, the second unit being movable between a contact position in which the developer carrying member contacts the image bearing member and a spaced position in which the developer carrying member is spaced from the image bearing member; a force receiving portion (44b, 44h) for receiving from the image forming apparatus a force for moving the second unit from the contact position to the spaced position, the force receiving portion being provided on the second unit; and an urging portion; the image forming apparatus including: a mounting portion for detachably mounting the process cartridge; and an engageable member (61, 71) engageable with the force receiving portion, the system being characterized in that the engageable member is movable between a first position for maintaining the second unit in the spaced position by engaging with the force receiving portion, a second position for permitting movement of the second unit from the spaced position to the contact position in image forming operation, and a third position for permitting the process cartridge to be mounted, by the engageable member being pressed by the urging portion to retract, when the process cartridge is mounted to the mounting portion. a first unit having an image bearing member; a second unit having a developer carrying member, the second unit being movable between a contact position in which the developer carrying member contacts the image bearing member and a spaced position in which the developer carrying member is spaced from the image bearing member; a force receiving portion (44b, 44h) for receiving from the image forming apparatus a force for moving the second unit from the contact position to the spaced position, the force receiving portion being provided on the second unit; and an urging portion; the image forming apparatus including: a mounting portion for detachably mounting the process cartridge; and an engageable member (61, 71) engageable with the force receiving portion, the system being characterized in that the engageable member is movable between a first position for maintaining the second unit in the spaced position by engaging with the force receiving portion, a second position for permitting movement of the second unit from the spaced position to the contact position in image forming operation, and a third position for permitting the process cartridge to be mounted, by the engageable member being pressed by the urging portion to retract, when the process cartridge is mounted to the mounting portion. a mounting portion for detachably mounting the process cartridge; and an engageable member (61, 71) engageable with the force receiving portion, the system being characterized in that the engageable member is movable between a first position for maintaining the second unit in the spaced position by engaging with the force receiving portion, a second position for permitting movement of the second unit from the spaced position to the contact position in image forming operation, and a third position for permitting the process cartridge to be mounted, by the engageable member being pressed by the urging portion to retract, when the process cartridge is mounted to the mounting portion.