  We show that every non-degenerate homogeneous plane continuum is homeomorphic
to either the unit circle, the pseudo-arc, or the circle of pseudo-arcs. It
follows that any planar homogenous compactum has the form $X \times Z$, where
$X$ is a either a point or one of these three homogeneous plane continua, and
$Z$ is a finite set or the Cantor set. The main technical result in this paper
is a new characterization of the pseudo-arc: a non-degenerate continuum is
homeomorphic to the pseudo-arc if and only if it is hereditarily indecomposable
and has span zero.

General Topology