  In the chiral $SU(15)$ gauge theory presented here, the quarks and leptons
are bound states ("prebaryons") of massless preons. The Standard Model charges
of the preons imply 3 generations of quarks and leptons, plus some vectorlike
fermions lighter than the confining scale $\Lambda_{\rm pre}$. Under certain
assumptions about the chiral dynamics, bound states of two prebaryons behave as
Higgs fields. The QCD and electroweak groups may unify above $\Lambda_{\rm
pre}$, while $SU(15)$ prevents rapid proton decay.
