A bi-directional clutch for operating a window dressing such as a roller shade includes a protective guard for securing the window dressing to a stationary structure, a gear box for transmitting rotation to an output member in response to the operation of an elongated operating member such as a cord, and an antirotational member that prevents the undesirable operation of the output member. The output member is coupled to the window dressing. The gear box includes a gear pulley coupled to the elongated operating member, a planetary gear and a stationary gear. The gear box is arranged and constructed to transmit motion to the output member in response to the activation of the elongated operating member, at a predetermined mechanical advantage.