This book includes small and large scale applications of super- conductivity. Part I, SQUIDs, comprises about 75% of this volume, and is devoted to small scale applications, mainly . uperconducting QUantum Interference Devices (SQUIDs), and the remainder, Part H, Machines, presents an updated review of large scale applications of superconduc- tivity. The present book combined with the previous book Superconducting Machines and Devices: Large Systems Applications edited by S. Foner and B. B. Schwartz, Plenum Press, New York (1974) represents a detailed and most up-to-date review of the applications of superconducting tech- nology. The text of the current book is suitable for advanced undergrad- uates or graduate students in applied physics and engineering courses. The book should be valuable to scientists, engineers and technologists interested in the current status and future applications of superconduc- tivity technology. The last 7 chapters in Part I review the major nation- al efforts on small scale technology and should prove useful for industrial and government planners as weIl as scientists and engineers.