Stjepan Planić (Zagreb, 1900 – Zagreb, 1980) was an architect whose extensive and valuable collection of architectural designs and continuous dedication to promoting humanistic architecture made him one of the key cofounders of Croatian modern architecture. After finishing Public Technical High School in 1920 he worked for Rudolf Lubinski and later for the Ivančić & Wolkenfeld Building Company. On Drago Ibler’s invitation in 1926 he enrolled at the Royal Academy of Arts in Zagreb as a member of the first generation of future architecture graduates. In 1927 he opened his own architectonic studio. As a member of the group of progressive thinkers known as the “Earth” (Zemlja, 1929 – 1935) Planić promoted social awareness in modern architecture. In numerous professional papers he strived to convey his idea of housing culture not only to peers, but to wider audiences as well. Early in his career he edited and co-authored The Problems of Modern Architecture – One Ought to Know. The book consisted of texts by Croatian architects presenting the fundamental postulates of modern architecture. It was published early in 1932 and its introduction features a publication of the founding declaration of the 1928 International Congress of Modern Architects (CIAM). For almost half a century it will remain the only book on modernist architecture in inter-war Croatia. His second book Housing Culture was about to be published not long before he passed away. He envisioned it as a picture book bringing modern architecture and its ideas closer to the youngest audience. The book was posthumously released in 1985. His inclination to individualized expression is noticeable in all of his architectural designs and due to his use of round forms and locally available materials he is often categorised in the organic style of modern architecture.