Abstract: Methods and systems that enable searching with clustering in information access systems are described. The methods of clustering operate on a collection of materials wherein each item in the collection may be associated with one or more properties. An original subset of materials is selected from the collection and relevant properties associated with the subset of materials are clustered into property clusters. Each property cluster generally contains properties that are more similar to each other than to properties in a different property cluster. The property clusters can be used to respond to the query. A mapping function can be used to identify a set of materials that correspond to each property cluster based on the associations between individual items and properties. The property clusters can also be used for iterative query refinement.