  We consider how tetraquarks can affect the chiral phase transition in
theories like QCD, with light quarks coupled to three colors. For two flavors
the tetraquark field is an isosinglet, and its effect is minimal. For three
flavors, however, the tetraquark field transforms in the same representation of
the chiral symmetry group as the usual chiral order parameter, and so for very
light quarks there may be two chiral phase transitions, which are both of first
order. In QCD, results from the lattice indicate that any transition from the
tetraquark condensate is a smooth crossover. In the plane of temperature and
quark chemical potential, though, a crossover line for the tetraquark
condensate is naturally related to the transition line for color
superconductivity. For four flavors we suggest that a triquark field,
antisymmetric in both flavor and color, combine to form hexaquarks.
