The Henry Demarest Lloyd Papers have constituted a major research source for two biographers. From her close personal associations and memories and from the records, Caro Lloyd wrote Henry Demarest Lloyd, 1847-1903; A Biography (2 volumes. New York and London, G.P. Putnam's Sons, 1912), which displayed the great affection and adulation marking her regard for her brother. In 1937 a detailed study of Lloyd's intellectual development and career as a reformer was undertaken by Chester McArthur Destler. Also highly laudatory in its conclusions, this study was published as Henry Demarest Lloyd and the Empire of Reform (Philadelphia, University of Pennsylvania Press, 1963).
