It reproduces more than 400 prints from Posada's vast production, collected by Pablo O'Higgins from those that could be located and identified at the time. The images of these high-spirited, at times macabre, broadsheets include the famous calaveras, or skeleton caricatures, along with illustrations for songs, corridos (traditional ballads), and religious prayers. With their striking visual qualities, they enriched the tradition of the popular Mexican print. In addition to the images, the book includes an introduction by Frances Toor, the legendary editor of the magazine Mexican Folkways, and an essay by Diego Rivera on Posada. According to Rivera, the importance of this publication resided in its refusal to allow Posada to sink into oblivion. It was therefore a "cornerstone," "the first permanent record of the work of Jose Guadalupe Posada." His illustrations, in spite of being appreciated and still in use at the time, circulated without his name and the recognition he deserved.