Previous work on growth-rate dispersion has shown how to calculate crystal-size distributions when the growth-rate distribution is known and how to calculate rite growth rate distribution when the crystal-size distribution is known. There is a significant lack of information, however on how growth-rate dispersion is affected by changes in system conditions like supersaturation, stirring speed slurry density, or temperature. In this work, the growth-rate distributions of sodium nitrate secondary nuclei are characterized as a function of the nucleation and growing supersaturations. Growth-rate dispersion is characterized by analyzing the mean, spread, and shape of the growth-rate distribution. This provides a means of determining the factors that cause and control growth-rate dispersion. The analysis of this experimental work provides valuable insight into the relationships among supersaturation conditions, strain, and dislocation density. The average growth rates of secondary nuclei are dislocation controlled at low growing super-saturations and strain controlled at high growing supersaturations, where increasing the nucleation supersaturation causes an increase in both dislocation density and strain. Increasing strain by itself will decrease growth rates, while increasing dislocation density by itself will increase growth rates. This work also suggests that harsh system conditions can affect growth rates adversely.