The utilization of the Biginelli reaction, a one-pot condensation of an aldehyde, a β-keto ester, and urea, is described. This reaction involves a number of individual steps, each of which is accessible to first-year organic students. The product, a 3,4-dihydropyrimidinone, is a member of a medicinally useful class of compounds. The reaction is simple to perform and the product precipitates from solution in an extremely pure form.