Isolated vertically aligned carbon nanofibers (VACNFs) have been grown using do plasma-enhanced chemical vapor deposition, and the effects of the growth conditions on VACNF morphology and composition have been determined in substantial detail. The dependence of the growth rate, tip and base diameters, and chemical composition, of isolated VACNFs on the growth parameters is described, including the effects of plasma power and gas mixture. Phenomenological models explaining the observed growth behavior are presented. The results indicate the importance of plasma control for the deterministic growth of isolated VACNFs, which are promising elements for the fabrication of practical nanoscale devices.