Methods, systems, and apparatus, including computer programs encoded on a computer storage medium, for building and serving dynamic product advertisements. A request is received for content including request data. Product data is accessed representing multiple product records, each associated with a different product. Multiple matching rules are applied to each of the product records in order to identify a subset of product records satisfying the matching rules. For each of the product records satisfying the matching rules, multiple scores are generated, each score representing the relevance of the product to the request based on the request data. The scores are aggregated. One or more of the product records are selected based at least on the aggregate scores. A dynamic product content item is served in response to the request featuring the products associated with the one or more selected product records.