Abstract: A cat litter box comprising a generally parallelepiped housing installed in a window opening of a dwelling. An expandable curtain enshrouding the housing permits unit width to be adjusted for different window frames. An internal partition divides the housing interior into a litter box compartment and an adjoining entrance foyer. The compartment holds a conventional litter box. One compartment wall comprises a pivoting shelf that opens for litter box servicing. The foyer permits entry into the housing while a port penetrating the partition permits movement between the foyer and the compartment. A capture system in the foyer recovers unused litter and other debris as a cat moves over it. The capture system comprises a storage tray with a perforated lid. The recovered litter may be transferred from the tray to the litter box during servicing. A distraction window increases a cat's residence time in the foyer.