ISAAGNY, the Independent Schools Admissions Association of Greater New York, has always been THE group for elite NYC private schools. This group, made up of admissions directors and heads of school, sets admissions policies, timelines, and testing for member schools. New schools' rite of passage has traditionally been to gain ISAAGNY membership.
Fascinatingly, new kid in town Avenues (opened in Sept. 2012) is not a member and so has benefited by administering its own admissions policies, such as Early Decision, absorbing new families before they even hear from competitor Manhattan and Brooklyn private schools.
Now established and prestigious Horace Mann has LEFT ISAAGNY. This February, for the first time ever, Horace Mann announced on its website:
We notify families of the admission decision in the first two weeks of February.
ISAAGNY member schools are not notifying for kindergarten until Friday.
Meanwhile, Horace Mann maintains that the ERB/WISC/ECAA is a useful kindergarten assessment that they will continue to require even as ISAAGNY schools drop it in 2014. From Horace Mann's website: