One variation of a method for selectively serving advertising content comprises: receiving identification of an advertisement slot loaded within a webpage; receiving a set of advertisement slot characteristics corresponding to the advertisement slot; accessing a model associating advertisement slot characteristics and user interactions with advertisements; for each target outcome, in a set of target outcomes, calculating an outcome score for the advertisement slot based on the set of advertisement slot characteristics and the model, the outcome score representing a probability of the user interacting with advertising content, presented within the advertisement slot, according to the target outcome; in response to a first outcome score, corresponding to a first target outcome, in the set of target outcomes, exceeding each other outcome score, assigning the first target outcome to the advertisement slot; and selecting a first advertisement, designating the first target outcome, for presentation within the advertisement slot.