Isaiah Berlin was a prolific letter-writer. He conversed on all manner of subjects, with a wide variety of correspondents, and a selection of his letters have been published in four chronologically ordered volumes: Flourishing, 1928-1946; Enlightening, 1946-1960; Building, 1960-1975; and Affirming, 1975-1997. Bibliographical references for each volume can be found in the IBO Catalogue. Since the publication of each volume, new material has come to light, and the best of this is made available by the IBO in online PDF supplements (details below, and in the Catalogue). The originals of Berlin's letters are mostly kept in the Bodleian Library in Oxford (search the Bodleian Catalogue).
Hardback 2009, Paperback 2011; edited by Henry Hardy and Jennifer Holmes; pictured is the paperback jacket.
Letters that have emerged since publication have been reproduced in the IBO PDF Supplement Bib.270(s)
Hardback 2013, Paperback 2016; edited by Henry Hardy and Mark Pottle; pictured is the paperback jacket.
A selection of the letters that have emerged since publication are reproduced in an IBO PDF Bib.273(s)
Hardback 2015, Paperback 2017; edited by Henry Hardy and Mark Pottle; pictured is the paperback jacket.
Supplementary letters for this period are reproduced in two online IBO PDFs: the first offers general correspondence, Bib.286(s1); the second letters/notes that are specifically relevant to an interpretation of Berlin's thought, Bib.286(s2)