AbstractDuring initial production of a new product prior to actual production, the decrease in the fraction defective of units produced can be observed as personnel gather experience and the faults in the product's design, manufacturing, etc. are removed. This paper discusses an initial production process control based on a quality growth model proposed here. The model describes a continuing reduction in the cumulative defect rate defined by the ratio of the cumulative number of defective units to that of produced units. A stopping rule is also investigated for determining when to discontinue the initial control of the production process and proceed to the actual production stage. Further, a numerical example of the application is presented.