Water-based Ready-to-use formulations and concentrates were developed for a commercial fungicide. A systematic screening approach was used to develop the formulations. Control of crystal growth and chemical stability of the fungicide were primary challenges. The concentrate consists of an optimized combination of pyrrolidone copolymers, water-insoluble or sparingly water-soluble cosolvent, and anionic emulsifiers. A rationale for the unique Ready-to-use compositions will be provided. The formulations were successfully applied to the strobilurin fungicides Kresoxin-methyl and Azoxistrobin. The formulation approach can be extended to deliver other hydrophobic compounds in water at high dilution.