A slide rail assembly includes first and second rails. The second rail, slidable relative to the first rail, has a mounting hole. A connecting device includes first and second units, an engaging element, and an adjusting element. The second unit has a transverse guiding portion located at its counterpart of the first unit. The engaging element, connected to the second unit, has an engaging portion partially located in the mounting hole to connect the connecting device to the second rail. The adjusting element is connected to both units. The second unit is displaceable in response to rotation of the adjusting element, thereby enabling displacement of the engaging portion relative to the mounting hole.