  The processes that disperse the products of massive stars from their birth
sites play a fundamental role in determining the observed abundances. I discuss
parameterizations for element dispersal and their roles in chemical evolution,
with an emphasis on understanding present-day dispersion and homogeneity in
metallicity. Turbulence dominates mixing processes, with characteristic
timescales of order 10^8 yr, implying significant dilution of metals into the
ISM. This permits a rough estimate of the metallicity distribution function of
enrichment events. Many systems, including the Milky Way and nearby galaxies,
show metallicity dispersions that as yet appear consistent with pure
inhomogeneous evolution. There are also systems like I Zw~18 that show strong
homogenization, perhaps tied to small galaxy size, high star formation rate,
and/or superwinds.
