The paper birefly reviews published mix proportioning methods for concrete incorporating fly ash and proposes a new procedure that attempts to provide fly ash concrete of constant paste quality. In this procedure, the adjustment to provide the necessary workability is accomplished by varying the amount of aggregate used, rather than the water content or the proportion of cement or fly ash. The method is self-contained, requiring no reference to any other formal mix proportioning procedure. The suggested trials result in sufficient data for both strength and workability so that fly ash mixes can be designed confidently with reference to the properties of the speicfic available fly ashes and aggregates.