The magnetic shielding and its polarizabilities, have been calculated for tertiary butyl alcohol and tertiary butyl amine. These have been used to rationalise the solvent shifts of the proton spectra of the interesting cosolvent systems with water recently measured by Kipkemboi, et al. Continuum solvation calculations and calculations of Buckingham A and B for relevant nuclei are presented. New parameters relevant to the 13C, 15N and 17O NMR spectra in the same systems have been calculated. There is wider discussion of the validity of chemical shift estimation methods. New calculations on the related molecules Si(CH3)4 (TMS), neo-pentane C(CH3)4 and tetramethyl ammonium cation N(CH3)4(+) have also been presented. KEY WORDS: Solvent effects, Magnetic shielding, Tertiary butyl alcohol, Tertiary butyl amine, Continuum solvation calculations, Chemical shift estimation methods Bull. Chem. Soc. Ethiop. 2005, 19(2), 243-255.