Book excerpt: Networks and Marginality: Life in a Mexican Shantytown describes the life and survival of economically marginal or poor people in Cerrada del Cóndor, a shantytown of about 200 houses in the southern part of Mexico City. The field work is carried out between 1969 and 1971 using combined anthropological and quantitative methods. This book is composed of 10 chapters and begins with an overview of the theoretical concepts essential for an adequate comprehension of the later chapters, followed by a summary of the development and evolution of Mexico City as they relate to Cerrada del Cóndor. Considerable chapters examine the migration process, the economy, the family and kinship patterns, and the reciprocity networks and associated mechanisms of survival value in the shantytown. The remaining chapters discuss some of the relevant theoretical points raised by the findings, including the reciprocity, the confianza concept, and the importance of informal economic exchange in complex urban societies. This book will prove useful to economists, anthropologists, social scientists, and researchers.