This thesis explores the influences of American architecture on Hendrik Petrus Berlage, which focuses on his design principles and the American principles that manifest into his work. His rationalist approach, which demonstrates structural expression, proportional systems, and controlled use of ornamentation, was shaped by 19th century American architecture, deducted by his studies of Henry Hobson Richardson. His interest in the style extends to the 1911 trip to United States, which further shapes his influences. Furthermore, Beurs van Berlage reveals similarities in design approaches through structure, ornamentation, materiality, and geometric organization. The thesis concludes that these principles were taken and reinterpreted by Berlage.