The key developments in the Abolitionist Movement were the ending of the Atlantic slave trade, stopping of the slavery, and also giving rights to the slaves as all other people.
The Abolitionist Movement was a movement that put in a lot of effort in stopping all the things connected with the slavery. First thing was to stop the Atlantic slave trade, thus eliminating the possibility of new slaves coming on the scene, and gradually they made to achieve that. Than the slaves had to be released, and further more to be granted equal rights as all the other people. That turned to be a much larger problem though, as lot of people were not willing to give up on their free labor force, lose profit, and also didn't wanted to be equal to people that they saw as primitive. That took much longer time, as well as a large scale civil war, but eventually the goal was achieved.