The Universalist General Convention commended the second Sunday in June, or as near as convenient, as Children’s Sunday. Don’t know if there was a fund-raising or denominational programatic piece — bet there was, though — and will report back if I find anything, including the resolution that began the observance.
In June of 1856 Rev. Charles H. Leonard, minister of the Universalist Church in Chelsea,MA instituted the first Children’s Sunday. Twelve years later delegates to the Universalist General Convention set apart the second Sunday in June as a day to celebrate as Children in our churches. A celebration which has spread beyond Unitarian Universalist congregations and now occurs on this Sunday in many Protestant churches.