Results from a series of experiments conducted under controlled environmental conditions have been re-analyzed for a quantitative data base predicting gross morphological changes in the soybean (Glycine max (L.) Merr.) plant. Such information is needed for the construction of plant growth models describing detailed organ-by-organ carbon and nitrogen budgets in the plant, as well as the expansion of a crop canopy of leaves as the growing season progresses. Leaf and stem expansion rates were monitored to calculate appearance rates for new organs on the main shoot and axillary branches. Leaf expansion rate, when expressed per apparent plastochron (a time period derived from leaf appearance rates on the main shoot) was unaffected by temperature, but was affected by the main shoot number or the ultimate size of the expanding trifoliolate. From concurrent dry matter determinations, minimum dry matter required for leaf expansion was estimated to be about 0.17 g/dm2 leaf area, with maximum values of 0.35 g/dm2 for plants growing in a cool temperature (18 C) or in a relatively rich CO2 atmosphere (1,000 ppm v/v). Values for pod and internode growth rates are also given. Other relevant published and unpublished data are discussed to depict the general kinds of data sets needed for model construction.