  We discuss the production of two hadrons in e+e- annihilation within the
framework of perturbative QCD. The cross section for this process is calculated
to next-to-leading order accuracy with a selection of variables that allows the
consideration of events where the two hadrons are detected in the same jet. In
this configuration we contemplate the possibility that the hadrons come from a
double fragmentation of a single parton. The double-fragmentation functions
required to describe the transition of a parton to two hadrons are also
necessary to completely factorize all collinear singularities. We explicitly
show that factorization applies to next-to-leading order in the case of
two-hadron production.
