Of the mechanisms proposed to bring gaseous fuel into the central starburst regions of a galaxy, non-axisymmetries in the gravitational potential set up by interactions or by bars are among the most promising. Nevertheless, direct observational evidence for a connection between interactions and bars on the one hand, and starburst (as well as AGN) activity on the other, remains patchy. These general issues are reviewed before proceeding to discuss, within this context, massive star formation in the circumnuclear regions of spiral galaxies, in particular star-forming nuclear rings and pseudo-rings. Such rings are common, and are closely linked to the dynamics of their host galaxy, which in almost all cases is barred. The possible existence of a population of nuclear rings on scales which are too small for detection with standard ground- or even space-based techniques will be discussed.