This article is from the Hanggliding and Paragliding FAQ, by Joao Geada with numerous contributions by others.
A hangglider is somewhat more difficult to fly under tow, and the
pilot must also be aware of the various things that can go wrong in
order to react appropriately. The USHGA has tow administrators who can
rate people for tow. Most of those are also instructors and can train
people to tow safely.