In this research, we explore nested or hierarchical query segmentation4, where segments are defined recursively as consisting of contiguous sequences of segments or query words, as a more effective representation of a query. We design a lightweight and unsupervised nested segmentation scheme, and propose how to use the tree arising out of the nested representation of a query to improve ranking performance. We show that nested segmentation can lead to significant gains over stateof-the-art at segmentation strategies.