Abstract: A facility for producing an item recommendation for a selected user is described. The facility accesses an information resource that, for each of a number of buckets that each correspond to a different collection of personal information, identifies users for a members of the bucket into each of whom the entire collection of personal information applies. The facility selects a bucket among the plurality of buckets of which the selected user is a member. The facility accesses a number of item ratings that were each contributed by a member of the selected bucket other than the selected user. For each item rated among the accessed item ratings, the facility aggregates the ratings of the item. On the basis of items' aggregated ratings, the facility selects one or more rated items for recommendation to the selected user.