Theoretical studies of carbon and metallic clusters using techniques from condensed matter and nuclear physics are used to elucidate the electronic, magnetic and structural properties of a variety of interesting systems. These include fullerenes as well as alkali metal clusters. Techniques used include LCAO, LDA and Greens function methods. Particular attention is paid to collective effects, the effect of substitution in metal alloy systems, spectroscopic properties such as the Jahn-Teller effect and the relationship of structure to magnetic properties.