The four-volume set LNCS 16483-16486 constitutes the refereed conference proceedings of the 48th European Conference on Information Retrieval, ECIR 2026, held in Delft, The Netherlands, during March 29&April 2, 2026. The 46 full papers and 37 short papers presented together with 10 findings papers, 9 reproducibility papers, 17 resource papers, 11 workshop papers, 7 tutorial papers, 19 IR4Good papers, 13 demo papers, 14 doctoral consortium papers, 10 industry track papers, and 16 CLEF overview papers, were carefully reviewed and selected from 530 submissions. The papers were organized in the four volumes as follows:  Volume 1: Full Papers Volume 2: Full Papers and Short Papers Volume 3: Reproducibility Papers, Workshop Papers, IR for Good papers, and Doctoral Consortium Papers Volume 4: Tutorial Papers, Industry Papers, Demo Papers, CLEF Overview Papers, and Resource Papers.