Seed development in Jatropha curcas L. was studied with respect to phenology, oil content, lipid profile and concentration of sterols. Seeds were collected at various stages of development starting from one week after fertilization and in an interval of five days thereafter till maturity. These were classified as stage I to stage VII. Moisture content of the seeds ranged from 8.8 to 90.3%; the lowest in mature seeds in stage VII and highest in stage I. The seed area increased as the seed grew from stage I to stage VI (0.2-10.2mm(2) per seed), however, the seed area shrunk at stage VII. Increase in seed area corresponded to increase in fresh weight of the seeds. (1)H NMR spectroscopy of hexane extracts made at different stages of seed development revealed the presence of free fatty acids (FFA), methyl esters of fatty acids (FAME) and triglycerol esters (TAG), along with small quantity of sterols. The young seeds synthesized predominantly polar lipids. Lipid synthesis was noticed nearly three weeks after fertilization. From the fourth week the seeds actively synthesized TAG. Stage III is a turning point in seed development since at this stage, the concentration of sterols decreased to negligible, there was very little FAME formation, accumulation of TAG increased substantially, and there was a sudden decrease in FFA concentration. The findings can be helpful in understanding the biosynthesis and in efforts to improve biosynthesis of TAG and reduce FFA content in the mature seeds.