Question: how many episodes are in a season of once upon a time
Answer: Season Episodes Originally aired Nielsen ratings First aired Last aired Viewers ( millions ) Viewers rank 18 -- 49 rating / share 18 - 49 rank 22 October 23 , 2011 ( 2011 - 10 - 23 ) May 13 , 2012 ( 2012 - 05 - 13 ) 11.