The synthesis of highly ordered carbonaceous materials, possessing graphite layers arrayed in a variety of orientations, has been the subject of a disparate and burgeoning literature over the past decade. This interest has been fuelled by the unique chemical and physical properties associated with these carbon structures that can be exploited in adsorption, catalysis, gas storage and electronics applications. Carbon nanofibers (or nanofilaments), the focus of this Review, display unique mechanical and electrical properties that have been used to good effect as additives for reinforcing materials or as a means of achieving enhanced conductivity. Graphitic carbon materials can be readily synthesized by arc discharge and plasma decomposition but such methodologies also yield an appreciable amorphous component, necessitating the incorporation of a purification stage. The growth of ordered carbon from metal catalysts, either supported or unsupported, has emerged as a viable low cost and highly selective route to a graphitic filamentous product. We consider the critical catalyst characteristics that have been shown to impact on the dimensions and structure of the carbon product and provide an evaluation of the growth mechanisms that have been proposed in the literature. The specific and generic features of catalytic carbon growth are discussed by taking, as a model system, the production of filamentous carbon via the decomposition of ethylene over supported nickel catalysts. The effects of catalyst preparation, the nature of the support and metal loading on carbon growth are discussed and the promotional effect of alkali metals and halogens as dopants is addressed. The characteristics of the carbonaceous product are illustrated through a combination of scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM) and temperature programmed oxidation (TPO). Carbon yield and structure are linked to the supported nickel particle size distribution/electronic structure and reaction time/temperature.