The article reviews the contribution of Alexey Vasilievich Lebedev (1888 - 1944) to the study of the works created by F.S. Rokotov, outstanding Russian artist of the 18th century. Lebedev conducted his research in the 1920-1930s, i.e. the early years of Soviet art studies. The expansion of museum collections and identification of previously unknown works stored in private collections allowed art historians to ascertain the specific features of the creative method practiced by the 18th century Russian masters, suggest new ideas, make attributions, and expand the range of research issues. Lebedev's approach is examined using as a case study his work «F.S. Rokotov (essays for a monograph)» (1941). This work, dedicated to «identifying what is truly Rokotov’s» in the artist's legacy, became fundamental for the next generation of researchers. It is concluded that A.V. Lebedev’s publications are highly relevant to the studies of the historiography of Rokotov's creativity.