Book excerpt: This book is designed for two primary audiences - those interested in working in subsistence marketplaces, as well as those interested in applying the lessons learned (in such extreme contexts) to their own contexts, such as in advanced economies or in higher-income segments of developing economies. We aim to reach a diverse audience including practitioners in business, government, and social sectors; and researchers, educators, and students. We develop the notion of bottom-up enterprises learned through practice in extreme, i.e., resource-constrained, settings. Sometimes, the most insightful lessons for all settings come from such discovery. The book begins with a journey of immersion and reflection in the first part, followed by explicit discussions of lessons learned in the second section. In the third and last part, we broaden the dialogue to include bottom-up applications to a variety of settings and operations. Even for those not working in subsistence marketplaces, there is significant value in understanding the implications of these bottom-up approaches to their own efforts. We illustrate a number of situations where our approaches have had impact in other domains.Finally, our sequencing here is bottom-up as well, beginning with a deep understanding of subsistence marketplaces, followed by the design of solutions and enterprise plans for them. After this, the discussion turns to lessons in running a bottom-up enterprise before moving on to the application of these lessons in a variety of contexts.There is an irony is writing a book about being bottom-up. The very act of writing about it is, in a sense, top-down. And so goes the dance between the bottom-up and the top-down that is detailed in this journey.