Abstract: A request for annotations identifying a user, an electronic content item (e.g., an electronic book), and a portion of the electronic content item is received from a client device. A set of annotations is identified that correspond to the identified portion of the electronic content item and an unlocked subset of this set of annotations is determined based on an access history of the identified user that indicates electronic content the identified user has previously accessed. At least one annotation from the unlocked subset is sent to the client device for presentation in conjunction with the identified electronic content item.