The definition of society is never changed overnight, but must be fostered by time. Even after a violent change a construction of the new social norm needs to manifest. A very successful social movement that comes to mind is the civil rights movement. Martin Luther King stressed non-violent protest which proved to be a huge element in their success. Though, much was accomplished by the movement, unjustness is still of major issue.
Social reality constructs peoples view of the world.
The elements of that reality are usually accepted as normal and common. Sometimes new elements of society are proposed, through laws, education, advertising and many institutions. When a norm or proposed norm is unfair many times people are sparked to do something about it. Protests are not always successful, but when done on a large enough scale are able to aware people about the issue.