In recognition to his competence, Alexandru Lapedatu was nominated between 1919 and 1922 as an expert in the Romanian delegation to the Paris Peace Conference (1918); the documents he authored were submitted by Romania to the Conference and were used by the Romanian Delegation as basis for the negotiations. Alexandru Lapedatu had cultural activities in various associations and foundations, such as in the Asociația Transilvană pentru Literatura Română și Cultura Poporului Român (ASTRA) (Transylvanian Association for the Romanian Literature and the Culture of the Romanian People) that proclaimed him honorific member (8/9 November 1924), then elected him member of the "demographic and ethnology-politic section" (14/15 September 1935). For ASTRA he provided funding, held conferences, supported the publication of the ASTRA library, and donated the Fund "Al. I. Lapedatu". Alexandru Lapedatu expressed his conviction that promoting the cultural development is an essential mission of the State and the nation, and proposed and implemented policies pursuing the enhancement of the cultural and artistic prestige of all cities, and of the country as a whole. Alexandru Lapedatu formulated the principles of the monument preservation and restoration already in 1911. Under his leadership, the Transylvania Section of the Historical Monuments Commission executed in 1929–1948 more than 240 conservation and restoration projects, addressing Romanian heritage such as antiques Roman and Dacian vestiges, medieval stone churches and monasteries, wooden architecture, rear glass painted icons, the Hunedoara and Bran Castles, the Suțu Palace and the Filipescu House in Bucharest etc. After 1918, the Commission for Historic Monuments also undertook large restoration works on monuments belonging to Hungarian or Saxon minorities including Roman Catholic or Evangelical churches in Cluj-Napoca, Sibiu, Brașov, Alba Iulia, Sighișoara etc. As Cults and Arts Minister for almost seven years, he pursued a wide the areas of activities:  The first challenging task of Alexandru Lapedatu as a minister has been to establish a legal frame for the cults in the unified Romania. He presented the statement of reasons for the law clarifying that in the united Romania, besides the Orthodox Church, the State recognized the following cults: Romanian Greek-Catholic (united), Catholic (of Latin, Greek and Armenian ritual), reformed (Calvin), evangelic-Lutheran, Unitarian, Mosaic, Muslim and finally Baptist (recognized only in Transylvania), each governed by a different legislation in the regions coming from Russia, Austria, Hungary, Bulgaria respectively the Kingdom of Romania.