To produce a comprehensive overview of macrophages and related cell types in a short review volume is an impossible task. When I selected the topics to be included, some equally important areas were omitted by necessity, and for this I apologize. My choices have been somewhat eclectic, touching subjects of personal interest (such as osteoclast biology and macrophage electrophysiology) or of current fashion (apopto sis, antigen processing, cell adhesion molecules). The book has also had to encompass areas of a more general flavor to provide balance for the general reader (such as reviews of...