The concept of “humanity”—the belief that “all humanity is one undivided and indivisible family”—has been created slowly in human consciousness since the fifteenth century. Humanity has found increasing expression in international law through the ending of slavery, the creation of “crimes against humanity,” and the advancement of human rights. This slow creation of humanity is described by reviewing the vital contributions of Bartolomé de Las Casas, Granville Sharp, Edmund Dene Morel, H. G. Wells, and Eleanor Roosevelt. Still, the creation of humanity is incomplete. The author's research on “identification with all humanity” is summarized. Finally, speculation is offered on the social and psychological foundations of identification with all humanity, on factors that undermine it, and on how it might be enlarged.