The aim of this paper has been to introduce self-consistency into a general, but necessarily rather oversimplified, method of molecular orbitals. Thus the non-linearity of the equations (19) has enabled us to deal in a systematic way with the charge distribution and bond properties of different conjugated molecules in a variety of configurations. Further analysis is required before term values can be predicted. The electro-affinity scale which may be set up for both $\sigma $ and $\pi $ electron pair bonds by means of this method turns out to be identical with that of Mulliken. A general account of the configurational theory of molecular structure has been given in an introductory section.