¹³C chemical shifts of pyridine, 2,2'-bipyridyl and 1,10-phenanthroline, and some of their methyl derivatives have been determined. All measurements were made on 0.25 M solutions in CDCl₃, thus enabling comparisons of chemical shifts and substituent effects to be made without complications from solvent effects. For the three classes of compounds, common correlations exist between ¹³C chemical shifts and both CNDO/2 and INDO calculated carbon total electron densities, with the results suggesting that CNDO/2 calculations provide more suitable data for empirical correlations with ¹³C chemical shifts.