The General Oblation Board is part of the Magisterium. The leader of the board is Marisa Coulter. Children called them the 'Gobblers,' although they were unaware of who was running it and what their intentions were. They were also unaware that it was part of the Magisterium.
One of the principal activities of the General Oblation Board is intercision, separating children from their dæmons to prevent them from attracting Dust. They believe that what they are doing is reversing original sin and making the world perfect again while in reality they are removing the children's souls.
Behind the scenes
Intercision is strongly similar to castration, which was practised by the Catholic Church of the real world in the Middle Ages. It's also similar to the early psychosurgical procedure of lobotomy, which involved severing the prefrontal cortex from the rest of the brain to produce effects akin to those of intercision.