  We present observational constraints on the nature of core-collapse
supernovae through an investigation into their radial distributions with
respect to those of young and old stellar populations within their host
galaxies, as traced by H-alpha emission and R-band light respectively. We
discuss results and the implications they have on the nature of supernova
progenitors, for a sample of 177 core-collapse supernovae. We find that the
radial positions of the overall core-collapse population closely follow the
radial distribution of H-alpha emission, implying that both are excellent
tracers of star formation within galaxies. Within this overall distribution we
find that there is a central deficit of SNII which is offset by a central
excess of SNIb/c. This implies a strong metallicity dependence on the relative
production of the two types, with SNIb/c arising from higher metallicity
progenitors than SNII. Separating the SNIb/c into individual classes we find
that a trend emerges in terms of progenitor metallicity going from SNII through
SNIb to SNIc, with the latter arising from the highest metallicity progenitors.
