Cathy et al.,
The group who used to meet at the Long School was the Ethical Society of Boston (a member of the American Ethical Union, the practitioners of "Ethical Culture"). It moved its weekly meetings to the Cambridge Center for Adult Education on Brattle St. near Church St. several years ago, and then this year to a building (with parking and bus and train access) on Concord Avenue in Belmont. They have a web site with lots's of information.
On Monday, December 17, 2012, cathy mclaughlin wrote:
no i didn't know about that sunday school group and it's a wonderful idea. i think there used to be a group of adults a long time ago who were humanists and met at longy on sundays but by the time our children were ready for something like that, i could not find a trace of them....