This thesis provides a background on the effects of applied and magnetic fields on crystallisation, and summarises the analytical techniques employed for characterisation and analysis. The study of applied fields was carried out on the crystallisation of one main system-solid nonadecane. This was then studied further to establish the effects of a solvent and a mixed solid system on the crystallisation of nonadecane. The systems studied were the crystallisations of: static and dynamic nonadecane, static and dynamic nonadecane in heptane, static and dynamic nonadecane and heneicosane, static and dynamic nonadecane and heneicosane in heptane and static and dynamic nonadecane and crude oil. The results of these studies showed that the magnetic and applied fields can affect electrostatic forces in molecular solids. It also showed that even the weakest of these forces, Van der Waals forces are affected by applied and magnetic fields.