The question of how a starburst is fuelled is closely related to some of the main outstanding problems in our understanding of starbursts, namely which combination of physical conditions leads to the triggering of the burst, and how long the burst can last. There is observational evidence that galactic bars and galaxy-galaxy interactions can lead to starburst activity, but this may be limited to specific and/or extreme cases, and not all bars or interactions lead to starbursts. Nuclear rings are mild circumnuclear starbursts, which are usually (but not always) triggered by bars, and which allow the study of both the dynamical relation of the host galaxy to the starburst, and the physical conditions of the latter. As an example, the case of NGC 278 is briefly reviewed.