Systems and methods for managing inventory in an online advertising system are described herein. The inventory may comprise advertisement (“ad”) impressions. In accordance with certain implementations, the systems and methods enable advertisers to target groups of inventory (e.g., “run of” inventory groups) made available by publishers and sold at a non-premium rate, while also enabling the publishers to selectively designate certain inventory within a given inventory group as premium. Inventory so designated is automatically excluded from an inventory group to which it would normally belong both during a booking process as well as during an ad serving process.