This is a collection of Harald Cramer's extensive works on number theory, probability, mathematical statistics and insurance mathematics. Many of these are not easily found nowadays in their original sources, for instance his pioneering works on risk theory published in jubliee volumes of the Skandia Insurance Company in 1930 and 1955. Despite their age, these eminentexamples of Cramer's expository style remain highly readable. Cramer was oneof the "fathers" of modern mathematical statistics. His famous book on the subject is still an important reference. His statistical papers includedhere were seminal to the subsequent development of the subject. The collection includes a complete bibliography of Cramer's work.