This text is an introduction to the interface between the actin cytoskeleton and the myriad of issues fundamental to the understanding of the nervous system. It covers the neurobiology of actin ranging from basic cellular organization and function to the roles of actin in the health and disease states of the nervous system. Its opening chapter presents the fundamental concepts required to appreciate the details of the molecular machinery that regulates actin in a cellular context, setting the stage for the first part of the book which reviews the neurobiology of actin at the cellular level. The latter section of the book then discusses the functions of actin in the context of neurobiological issues ranging from early development to synaptic function and disease states of the nervous system. This text is intended for neuroscientists interested in investigating the actin cytoskeleton in the context of their particular neuroscience research program, and its chapters are cross-referenced in order to assist readers in finding relevant information that is covered in greater depth in other chapters.