Andros offers multiple choices in high quality nightlife, though you shouldn't expect all night parties (like in Mykonos or Paros). Especially in Chora, one can find many cafes and bars, always crowded in summer.
The night begins with a nice movie at the open-air cinema in Chora. Afterwards, a visit to one of the many bars that stay open until early in the morning for music, dancing and drinking is always a challenge.
If you wish to leave Chora and try other destinations, there are many bars with good music and wonderful cocktails in Batsi. Those preferring Greek nightlife and music should definitely try greek nightclubs in Paleopoli and Gavrio, where dancing stops only in the morning.