The occurrence of starch and other soluble carbohydrates in the embryos and young developing fruits of 'Essex' soybeans were determined at anthesis and continuing 10 days after flowering (DAF). The embryo was shown to be filled with starch grains which disappeared with development. Digestion of embryo sections with a mixture of α- and β-amylases showed a rapid hydrolysis of the reserve starch, suggesting that enzymatic degradation in vivo may provide soluble sugars as substrates for embryo growth. Starch and soluble sugars in the young developing fruits were found to be high at anthesis and then decreased with fruit growth. However, 6-8 DAF, fruits 7-9 mm showed an influx of soluble sugars and an accumulation of starch. Glucose was the major component of the soluble sugars in the 80% ethanolic extracts analyzed by high performance thin-layer chromatography (HPTLC). Sucrose was present as a lesser component. Amylase activity was maximal at anthesis, but declined with increasing fruit size. Beta-amylase comprised a high percentage of the amylolytic activity in the developing fruits. Embryo development in fruits of greenhouse-grown plants collected 0, 2, 4, 6, 8, and 10 OAF closely paralleled that of greenhouse-grown plants sampled by morphological sizes. The stages of embryo development in fruits from field-grown plants sampled by morphological sizes were similar to anthesis, 2-5 mm, and 4-6 mm fruits of greenhouse-grown plants sampled by the same procedure. However, embryos of field-grown fruits 7-9 mm and 10-15 mm showed a more advanced growth than embryos of fruits of comparable size from greenhouse-grown plants. / M.S.