The Milford SF Writers' Conference (usually known as just "Milford") was an influential SF writers event founded in 1956 by Damon Knight, James Blish, and Judith Merril, in Milford, Pennsylvania where Merril then lived and where Knight had also lived.
It was a week-long meeting of a dozen writers who criticized each other work in intense detail. The sense of solidarity promoted, helped lead to the formation of SFWA. However, "disaffected authors began griping about a 'Milford Mafia' that was endangering SF's unique virtues by imposing literary standards essentially alien to the field."
Milford ended in 1972, coincidentally the year Blish moved over to the U.K. and started a similar conference there which still continues.