Affect’s Engine is an immersive ethnography of queer people of color on the social media platform Tumblr during its “peak” years, 2010–2015. Alexander Cho tells the story of Tumblr users and the hurricane of content that they circulated—and that circulated around them. Chronicling a formative time in social media history, Cho shows how a multiply minoritized population utilized Tumblr's unique structure to express, emote, and bond together as a survival strategy for resisting white supremacy and heteronormativity. Paying critical attention to user-facing design, he argues that this was not as possible on other platforms. The same features that drew queer people of color to Tumblr—to feel intensely—also explain why the platform did not succeed financially: its design did not instantiate a version of the good liberal subject—linear, singular, discrete, orderly, public, and market legible. While painting a vivid picture of a vital and bygone internet era, Cho asks readers to take seriously how affect is shaped by user-facing design on social media.