A publishing phenomenon and artistic project, cartonera was born in the wake of Argentina's 2001 economic crisis. Infused with a rebellious spirit, it has exploded in popularity, with hundreds of publishers across Latin America and Europe making colorful, low-cost books out of cardboard salvaged from the street. Taking Form, Making Worlds is the first comprehensive study of cartonera. Drawing on interdisciplinary research conducted across Mexico, Brazil, and Argentina, the authors show how this hands-on practice has fostered a politically engaged network of writers, artists, and readers. More than a social movement, cartonera uses texts, workshops, encounters, and exhibitions to foster community and engagement through open-ended forms that are at once artistic and social. For various groups including waste-pickers, Indigenous communities, rural children, and imprisoned women, cartonera provides a platform for unique stories and sparks collaborations that bring the walls of the "lettered city" tumbling down. In contexts of stigma and exclusion, cartonera collectives give form to a decolonial aesthetics of resistance, making possible a space of creative experimentation through which plural worlds can be brought to life.