This period was one of rapid growth for the Vienna Jewish community and also of intensified political anti-Semitism. Guedemann played an active role in developing communal institutions. With Joseph Bloch he organized the Oesterreichisch-Israelitische Union (1886) and also helped found the Israelitisch-Theologische Lehranstalt in 1893. Though Guedemann had not been trained as a historian, most of his numerous contributions to scholarship were in that field. His major work was Die Geschichte des Erziehungswesens und der Cultur der abendlaendischen Juden (3 vols., 1880–88), the first systematic attempt to examine some of the underlying trends and institutions of medieval Jewish life in terms of their non-Jewish milieu. Other works include Das juedische Unterrichtswesen waehrend der spanisch-arabischen Periode (1873) and Quellenschriften zur Geschichte des Unterrichts und der Erziehung bei den deutschen Juden (1892). During the final decades of his life Guedemann devoted an increasing amount of his scholarly output to the refutation of academic anti-Semitism. His Juedische Apologetik appeared in 1906.