Fast field-cycling (FFC) and rotating-frame nuclear magnetic resonance relaxometry were used to study molecular and collective dynamics in unilamellar liposome systems. Relaxation data for liposomes of diameter about 100 nm composed of 1,2-dimyristoyl-sn-glycero-3-posphocholine (DMPC) or 1,2-dioleoyl-sn-glycero-3-posphocholine (DOPC) were obtained. The Larmor frequency dependence of the spin-lattice relaxation rates was interpreted in terms of clearly defined relaxation mechanisms associated with the underlying molecular dynamics. The physical parameters obtained from the analysis are consistent with values available in the literature obtained from a range of experimental techniques. This work establishes the potential of our approach to study dynamics in liposomal samples of more complex lipid composition.