The distribution and morphology of H II regions in the discs of spirals has been examined in great detail for a set of objects imaged in Hα. In those with welldefined spiral arms the resonance structure is beautifully revealed by comparing the Hα flux with that from the underlying neutral gas. It is possible to infer the pattern speed of the density wave system, and even to deduce the presence, in some barred ojects, of leading arms. A statistical examination of the distributions of the diameters and fluxes of the H II regions with galactocentric radius suggests that there are differences in the stellar luminosity functions between the arms and the interarms discs of grand design spirals, but that the interstellar media surrounding the newly formed stars, on scales of kiloparsecs, show no physical differences between arms and the interarm zones. Finally an attempt is made to isolate those parameters in which grand design and flocculent galaxies differ, and which govern the star formation rates in their discs.