It has long been a major challenge to achieve synthetic control over size and monodispersity of gold thiolate nanoclusters. Among the reported Au-n thiolate clusters, Au-38 has been shown to be particularly stable but was only obtained as a minor product in previous syntheses. In this work, we report a bulk solution synthetic method that permits large-scale, facile synthesis of truly monodisperse Au-38 nanoclusters. This new method explores a two-phase ligand exchange process utilizing glutathione-capped Au-n clusters as the starting material. The ligand exchange process with neat dodecanethiols causes gold core etching and secondary growth of clusters, and eventually leads to monodisperse Au-38 clusters in high purity, which eliminates nontrivial postsynthetic separation steps. This method can be readily scaled up to synthesize Au-38(SC12H25)(24) in large quantities and thus makes the approach and Au-38 nanoclusters of broad utility.