The end of the 19th and the first half of the 20th centuries saw the emergence and intensive development of many disciplines in the technical sciences, and the laying of a groundwork for those disciplines in their current form. In Poland, a country deprived of independent statehood until 1918, this was additionally a period when native research centres and scientific schools came into being, and when Polish-language specialist literature emerged as well. One of the personages in question was Waclaw Moszynski, professor of the Warsaw Technical University, a pioneer of machine construction and mechanism theory, author of the first academic textbook in the field to be published in Poland. His contribution to the development of mechanism and machine theory is discussed on the basis of the history of the discipline until 1945 and in the context of his after-war activities. In particular, Moszynski's scientific achievements and his influence on the development of machine and mechanism theory in Poland are evaluated as well as his approach to matters of structure, kinematics and dynamics, with special focus on those of his formulations and solution to problems that appear particularly innovative and original. Moszynski's proposals, which made him a precursor of other disciplines, such as vibroacoustics, biomechanics and ergonomics, are also mentioned together with the role he played in development of the Warsaw research-and-teching centre in the field. The achievements and methods of the Warsaw school combined with those of other centres in Poland, which based on the earlier Lwów (Lvov) tradition, led to very significant research and educational accomplishments.