[3] President Obama presented the 2015 National Medal of Arts to The O'Neill on September 22, 2016.

It is home to the National Theater Institute[5] (established 1970), an intensive study-away semester for undergraduates.

The theater's campus, overlooking Long Island Sound in Waterford Beach Park, has four major performance spaces: two indoor and two outdoor.

[10] The estate, also known as Walnut Grove or Hammond Estate, was added to the National Register of Historic Places on September 21, 2005, for its architectural significance, and its associations with Revolutionary War Colonel William North and Edward Crowninshield Hammond, a wealthy railroad tycoon who frequently had the young O'Neill thrown off of the property when he owned it.

[1] The following is a list of plays, musicals, and performance pieces first developed at the O'Neill that have gone on to further success.