In 1908, a 7.1 equivalent magnitude earthquake struck Southern Italy. During the following year, the scientific community produced a considerable number of contributions, which were also encouraged by two competitions. In both competitions, the highest recognition was given to a Piedmont engineer—Arturo Danusso. Danusso derived the closed form equation of the response of an undamped linear elastic single-degree-of-freedom system to harmonic excitation. Thus, he suggested how to design a one-storey structure in order to minimize the amplification of its ground acceleration. In addition, he studied the case of a two-degree-of-freedom system, determining its two eigenfrequencies and concluding that the motion of each of the two masses can be reduced to the linear combination of the motions of two ideal simple systems subjected to given base motions. Danusso was probably the first to propose a dynamic analysis method rather than static lateral force analysis method and, possibly for the first time in earthquake engineering, he stated that seismic demand does not depend upon the ground motion characteristics alone. Danusso correctly solved the equations, and made some correct statements without writing any equations, as given in this paper. In addition, a brief account on Danusso’s life, Italian research after the 1908 earthquake, and Danusso’s influence on later Italian earthquake engineering will be presented.