In high-throughput screening (HTS) a robust assay is used to interrogate a large collection of small organic molecules in order to find compounds, hits, with a desired biological activity. The hits are then further explored by an iterative process where new compounds are designed, purchased, or synthesized, followed by an evaluation in one or more assays. Statistical molecular design (SMD) is a useful method to select a balanced, varied, and information-rich compound collection based on hits from HTS in order to create a foundation for development of optimized compounds with improved properties. In this chapter, we describe the use of SMD to explore a hit obtained from small-molecule screening.