A container storage and retrieval system (1) has first, second and third storage zones (2, 3, 4) for storing containers. The first storage zone (2) stores containers of product in frames (6), each frame (6) including a plurality of stacks (7) of containers. The second storage zone (3) stores containers of product in stacks (7). An automated retrieval system retrieves selected stacks of containers from the second storage zone (3) and replenishes the second zone (3) with containers by receiving frames (6). The third storage zone (4) includes a second automated retrieval system for retrieving selected partial stacks or stacks of containers, and replenishing the third storage zone with containers by receiving stacks from the second storage zone. Orders are collated by transferring a required number of complete frames (6) from the first storage zone (2), a required number of complete stacks (7) from the second storage zone (3) and a required number of stacks (7) or partial stacks from the third zone (4).