The entire state, it seems, turns out and rallies each spring for the Maine State Parade (first Sat. of May), a giant May Day parade and celebration each year in Lewiston. Expect a crush of diverse Maine  residents and an epic parade of colorful floats, music, and performers.
Every summer, the Bates Dance Festival (207/786-6381, http://abacus.bates.edu/dancefest ) attracts arts lovers from all over the country for its month-long spectrum of productions and workshops (be sure to call for dates and to reserve tickets—they sell out months ahead of time).
In August, you can get airborne at the Great Falls Balloon Festival (207/786-6674, www.greatfallsballoonfestival.org ) that takes over Lewiston  and Auburn  with festivities like pie-eating contests, concerts, crafts shows, and, of course, balloon rides.