This chapter looks at the works of Black American abolitionist Frederick Douglass. It argues that Douglass’ political thinking was shaped by his experiences as an enslaved, fugitive, and freed person. Douglass fought for the emancipation of all enslaved peoples across the USA as he believed all humans were born with a right to self-determination and freedom from enslavement. Additionally, Douglass believed slavery to be a deep violation of a person’s humanity. The chapter explains that Douglass’ abolitionism was grounded in natural rights theory. It looks at the legacy of the influential political theory on liberty that Douglass left behind. This was despite his complicated and often contradictory relationship to early women’s rights movements and his struggles to acknowledge the claims of Indigenous people.