This introduction presents an overview of the key concepts discussed in the subsequent chapters of this book. The book demonstrates the extent to which Marxist thought on the transition from capitalism to socialism provides an essential framework for understanding the successes and failures of recent and past attempts to construct socialist societies in Latin America and the Caribbean. It shows how Marxist theory can be used in a flexible, undogmatic manner to analyze, interpret, and critically reflect upon important instances of revolution and socio-political change in the modern world. The book suggests that efforts to build socialist societies in this important region clearly confirm the general proposition that there are no universal models for revolutionaries to follow in constructing socialism. It argues Marxism provides a powerful theoretical framework and an evolving body of revolutionary thought that has been and can be used to develop unique approaches to the revolutionary transformation of contemporary societies.