Dreisers two famous novels, Sister Carrie and Jennie Gerhardt, describe the life experiences of young women in big cities from lower-middle class during the social transformation of the United States in the late 19th century and early 20th century. Both novels have a strong tendency of naturalism, emphasizing the influence of environment on the personages destiny. This article compares “new women” and “real women”, inspecting the reasons for the two heroines completely different personalities and fates from the perspective of environmental sociology and peeping at the changes of average women.