  We discuss the fragmentation of a heavy quark to a baryon containing two
heavy quarks of mass $m_Q\gg\Lambda_{\rm QCD}$. In this limit the heavy quarks
first combine perturbatively into a compact diquark with a radius small
compared to $1/\Lambda_{\rm QCD}$, which interacts with the light hadronic
degrees of freedom exactly as does a heavy antiquark. The subsequent evolution
of this $QQ$ diquark to a $QQq$ baryon is identical to the fragmentation of a
heavy antiquark to a meson. We apply this analysis to the production of baryons
of the form $ccq$, $bbq$, and $bcq$.
