The conversion behavior of 10 oil shales from seven foreign and three domestic deposits has been studied by combining solid and liquid-state NMR measurements with material balance Fischer assay conversion data. The extent of aromatization of aliphatic carbons was determined. Between zero and 42% of the raw shale aliphatic carbon formed aromatic carbon during Fischer assay. For three of the shales there was more aromatic carbon in the residue after Fischer assay than in the raw shale Between 1:0 arid 20% of the raw shale aliphatic carbons ended up as aliphatic carbons 'ion the spent shale. Good correlations were found between the raw shale aliphatic carbon and carbon in the oil, and between the raw shale aromatic carbon and aromatic carbon on the spent shale simulated distillations and molecular weight determinations were performed shale oils. Greater than 50% of the oil.