This treatise describes a study of the conformation of nitrogen and phosphorus heterocyclic compounds using carbon-13 nuclear magnetic resonance methods. Isolation and assignment of the configuration of the three diasteroisomers of 1,3,5-trimethyl-4-phenylpiperidin-4- ol and the conformational effects in 2,2,6,6-tetramethyl substituted piperidine rings are described. In addition, the possibility of detecting boat (non-chair) conformations in 4-phenylpiperidin-4-ol derivatives is discussed. A carbon-13 nmr solvent study of the model system, 3-pi peridinol,was carried out to detect conformations where intramolecular hydrogen bonding interactions of the type -N--H-0- are possible. Several 3-tropinone derivatives were studied and evidence is presented for boat (non-chair) conformations where similar -N-C=0 and -N-H-0- interactions are implicated. Several representative six-membered ring phosphorus heterocycles were also studied in both the Pill and PIV oxidation states. Evidence is presented for the predominance of axial phenyl groups in several 1-phenylphosphorinanes. Additivity effects were derived for the phosphorus systems and comparisons made with analogous nitrogen heterocyclic parameters. The effect of the PIV oxidation state upon the chemical shifts in the aromatic ring of various phenyl phosphine oxides and the consequent valence bond structure of these oxides is reported. As a corollary, the chemical shifts of several dienones used as synthetic precursors in the above studies are reported and the effect of introducing a cross-conjugated double bond to the enone in acyclic and alicyclic systems is discussed.