This biography relies heavily on information first published in Pupin's still-in-print autobiography, From Immigrant to Inventor, which appeared in 1923 and won the Pulitzer Prize in 1924. Pupin's own book, noted for its simplicity and straightforward storytelling, is the better book, although this one records the years after that book's publication on to his death in 1935. Pupin's field was electricity and his inventions were based on research in radio transmission. The Pupin coil -- a spaced induction coil-- increased the distance over which telephone and telegraph messages could be sent with clarity by wire. He also did primary research in the development of X-ray equipment and revolutionized the teaching of electronic theory at Columbia University. These aspects of his career are made as simple as possible here and provide some insight into the place and methods of the inventors who improve and perfect existing products.