Historians are interested as never before in how people thought and felt about their lives. This turn to the personal has focused attention on the capacity of subjective records to illuminate both individual experiences and the wider world within which narrators lived. However, sources such as letters, diaries, memoirs and oral history have been the subject of intense debate over the last forty years, concerning both their value and the uses to which they can be put. Penny Summerfield traces the engagement of historians of the personal with notions of historical reliability, and with the issue of representativeness, and it explores the ways in which they have overcome the scepticism of earlier practitioners. Penny Summerfield is Emeritus Professor of Modern History at the University of Manchester and Honorary Vice-President of the Social History Society.