  Globular cluster ages are more than just lower limits to the age of the
universe; the distribution of ages constraints the timescales for galaxy
formation and chemical evolution. Globular cluster populations with different
metallicities have now been detected in many galaxies, and understanding how
these populations formed requires knowing their relative ages. We examined the
relative ages of the two M31 globular cluster populations using their color and
luminosity distributions and found that the metal-rich clusters could be up to
50% younger than the metal-poor clusters. While a small delay in the formation
of metal-rich clusters might be imposed by chemical enrichment timescales, a
large age gap demands a more detailed explanation. I outline several
possibilities and their promises and problems.

Astrophysics