In this work, the composition of rosin and resin samples was studied using novel capillary electrophoretic methods. Rosins are complex natural products which can have a tendency to crystallise when used in the soldering industry, causing problems in certain applications. The current tests for tendency to crystallise are not always accurate and there is no existing rapid screening method for the identification of a suitable batch of rosin. Thus far the resin acids present in rosins are generally analysed by GC-MS requiring derivatisation which is unable to separate all of the acids in question. In this work capillary electrophoresis methods for the analysis of the acid and neutral fractions of rosin samples were developed and applied to natural and modified rosin samples to investigate possible links between the presence and concentration of any compound and the rosin’s tendency to crystallise. A CE method was developed for the separation of nine resin acids for the first time. The simultaneous determination of nine neutral compounds present in rosin samples including terpenes and alcohols was also reported. The presence of neoabietic acid and elevated concentrations of abietic acid in rosin samples was found to indicate crystallisation of the rosin sample. The association constants of the inclusion complexes formed between the terpenes present in rosin samples and the cyclodextrins used for their analysis were investigated by affinity capillary electrophoresis. The surfactant-cyclodextrin interactions were found to be more significant than initially hypothesised. A rapid screening method for rosin samples was developed which could be used by industries to determine the suitability of a rosin batch for a particular use prior to purchasing.