Nucleation process is the most important stage in the formation of a crystal and has attracted the attention of researchers due to its importance in many technological and biological contexts. As the presence of impurities affects the nucleation process significantly, several studies have been made in the past to understand it. In this article is presented an overview of various studies made to understand the effect of soluble impurities on the crystal nucleation parameters of certain important materials in aqueous solution focusing the results reported by the research group of the present author.