Methods, systems, and apparatus, including computer programs encoded on a computer storage medium, for managing entities using observations. In one aspect, a method includes receiving data identifying an entity; generating a user interface document that, when rendered by a user device, presents a plurality of attribute values to a user and allows the user to modify one or more of the plurality of attribute values; and storing an observation in a data store, the observation including a user-modified value of one of the plurality of attribute values and a context including one or more of the presented attribute values.