 The autumn celebration in late 1621 that has become known as " The First Thanksgiving " was not known as such to the Pilgrims . The first " Thanksgiving " as the Pilgrims would have called it ( referring to solemn ceremony of praise and thanks to God for a congregation 's good fortune ) did not occur until 1623 , in response to the good news of the arrival of additional colonists and supplies . That event probably occurred in July and consisted of a full day of prayer and worship and probably very little revelry . 
