| Marx to James M Williamson. 6 January |
| Marx to Eleanor Marx. 8 January |
| Engels to Marx. 9 January |
| Marx to Eleanor Marx. 9 January |
| Marx to Engels. 10 January |
| Marx to Eleanor Marx. 10 January |
| Marx to Mrs James M Williamson. 11 January |
| Marx to James M Williamson. 13 January |
| Engels to Eduard Bernstein. 18 January |
| Engels to Eduard Bernstein. 8 February |
| Engels to Eduard Bernstein. 10 February |
| Engels to Karl Kautsky. 10 February |
| Engels to Laura Lafargue. 17 February |
| Engels to Eduard Bernstein. 27 February |
| Engels to Eduard Bernstein. l March |
| Engels to Karl Kautsky. 2 March |
| Engels to August Bebel. 7 March |
| Engels to Laura Lafargue. 10 March |
| Engels to Charles Longuet. 14 March |
| Engels to Friedrich Adolph Sorge. 14 March |
| Engels to Wilhelm Liebknecht. 14 March |
| Engels to Eduard Bernstein. 14 March |
| Engels to Johann Philipp Becker. 15 March |
| Engels to Friedrich Adolph Sorge. 15 March |
| Engels to Friedrich Lessner. 15 March |
| Engels to Pyotr Lavrov. 24 March |
| Engels to Laura Lafargue. 25 March |
| Engels to Friedrich Theodor Cuno. 29 March |
| Engels to Pyotr Lavrov. 2 April |
| Engels to Laura Lafargue. 11 April |
| Engels to Ferdinand Domela Nieuwenhuis. 11 April |
| Engels to Eduard Bernstein. 14 April |
| Engels to Thomas James Knowles. 17 April |
| Engels to Philipp Van Patten. 18 April |
| Engels to Thomas James Knowles. 20 April |
| Engels to Eduard Bernstein. 23 April |
| Engels to Friedrich Adolph Sorge. 24 April |
| Engels to Eduard Bernstein. 28 April |
| Engels to August Bebel. 30 April |
| Engels to Friedrich Adolph Sorge. 1 May |
| Engels to Wilhelm Liebknecht. 10 May |
| Engels to August Bebel. 10-11 May |
| Engels to Achille Loria. 20 May |
| Engels to Johann Philipp Becker. 22 May |
| Engels to Ludwig Klopfer. 22 May |
| Engels to Laura Lafargue. 22 May |
| Engels to Laura Lafargue. 2 June |
| Engels to Pasquale Martignetti. 19 June |
| Engels to Eduard Bernstein. 22 June |
| Engels to Laura Lafargue. 24 June |
| Engels to Friedrich Adolph Sorge. 29 June |
| Engels to Eduard Bernstein. 12-13 July |
| 25: Engels to Gabriel Deville. 12 August |
| Engels to Laura Lafargue. 19 August |
| Engels to Wilhelm Liebknecht. 21 August |
| Engels to Pasquale Martignetti. 22 August |
| Engels to Eduard Bernstein. 27 August |
| Engels to August Bebel. 30 August |
| Engels to Karl Kautsky. 18 September |
| Engels to Laura Lafargue. 19 September |
| Engels to Laura Lafargue. 3 October |
| Engels to Laura Lafargue. 15 October |
| Engels to Eduard Bernstein. 8 November |
| Engels to Vera Zasulich. 13 November |
| Engels to Max Quarsk. 13 November |
| Engels to Eduard Bernstein. 13 November |
| Engels to Johann Philipp Becker. 30 November |
| Engels to Karl Kautsky. 1 December |
| Engels to Laura Lafargue. 13 December |
| Engels to Eduard Bernstein. 22 December |