George and Lennie are outsiders in that they are not part of American society; they live on the fringes, never really belonging. They have no home, hold no permanent jobs, own nothing except what they can carry with them, and have no friends or families, except for each other. Although they dream an American Dream, they own no piece of it, and despite their most sincere efforts, never will because of social and economic forces beyond their control. George and Lennie represent the migrant class for whom Steinbeck felt great sympathy.
They are outsiders even among their peers. George and Lennie's traveling together sets them apart from the other men they encounter on the road and the ranches where they work. Their friendship seems strange to most observers. However, their society of two provides them with some sense of security and belonging. Lennie lives as an outsider among those who possess normal faculties, but George's loyalty to Lennie and his strong sense of responsibility for Lennie act to give him a place in society, such as it is and for as long as George can make it last.