  Recent proposals suggest that lasers based on narrow dipole-forbidden
transitions in cold alkaline earth atoms could achieve linewidths that are
orders of magnitude smaller than linewidths of any existing lasers. Here, we
demonstrate a laser based on the 7.5 kHz linewidth dipole forbidden $^3 $P$_1$
to $^1 $S$_0$ transition in laser-cooled and tightly confined $^{88}$Sr. We can
operate this laser in the bad-cavity regime, where coherence is primarily
stored in the atoms, or continuously tune to the more conventional good-cavity
regime, where coherence is primarily stored in the light field. We show that
the cold-atom gain medium can be repumped to achieve quasi steady-state lasing,
and demonstrate up to an order of magnitude suppression in the sensitivity of
laser frequency to changes in cavity length, the primary limitation for the
most frequency stable lasers today.
