Documents or document sets may be scored to reflect a value of an action, such as a selection for example, when an ad is served with the document (or a document belonging to a document set). A cost associated with the action with respect to an ad that was served with a document may then be adjusted using the score. For example, ad scores may be accepted or determined, and a document may be scored using the ad scores when served with the document and ad scores across a collection of documents to generate a document score. Each of the ad scores may indicate a value of an action with respect to an ad, such as a conversion rate, or a return on investment for an ad selection for example. Document scores used in this way may help advertisers get a more consistent cost per conversion, or return on investment, without requiring them to enter and manage various offers for various documents and/or various ad serving systems having various conversion rates or returns on investment.