Abstract: Methods and compositions for generating mixtures of product molecules from an initial chemical array are provided. In the subject methods, a chemical array of surface immobilized first moieties is subjected to cleavage conditions such that a composition of solution phase first moieties is produced. The resultant composition of solution phase first moieties is then contacted with one or more reactants to produce a mixture of product molecules that are different from the first moieties. Also provided are the arrays employed in the subject methods and kits for practicing the subject methods.