| Engels to Emma Adler 1 January |
| Engels to Ludwig Kugelmann 1 January |
| Engels to Hermann Schluter 1 January |
| Engels to Karl Kautsky 3 January |
| Engels to Ludwig Schorlemmer 3 January |
| Engels to Paul Stumpf 3 January |
| Engels to Pasquale Martignetti 8 January
|
| Engels to Victor Adler 9 January |
| Engels to Nikolai Danielson 9 January |
| Engels to Ludwig Kugelmann 9 January |
| Engels to Victor Adler 12 January |
| Engels to Karl Kautsky 12 January |
| Engels to Hermann Engels 12 January |
| Engels to Paul Lafargue 13-14 January |
| Engels to Friedrich Adolph Sorge 16 January
|
| Engels to Laura Lafargue 19 January |
| Engels to Paul Lafargue 22 January |
| Engels to Ferdinand Tonnies 24 January |
| Engels to Ludwig Kugelmann 25 January |
| Engels to Victor Adler 28 January |
| Engels to Wilhelm Ellenbogen 28 January |
| Engels to Vera Zasulich 30 January |
| Engels to Witold Jodko-Narkiewicz 2 February
|
| Engels to Richard Fischer 2 February |
| Engels to Georgi Plekhanov 8 February |
| Engels to Hermann Engels 8 February |
| Engels to Richard Fischer 12 February |
| Engels to Richard Fischer 13 February |
| Engels to Julius Motteler 23 February |
| Engels to Paul Lafargue 26 February |
| Engels to Georgi Plekhanov 26 February |
| Engels to Julius Motteler 2 March |
| Engels to Eduard Vailliant 5 March |
| Engels to Nikolai Danielson 5 March |
| Engels to Richard Fischer 8 March |
| Engels to Werner Sombart 11 March |
| Engels to Conrad Schmidt 12 March |
| Engels to Karl Kautsky 13 March |
| Engels to Victor Adler 16 March |
| Engels to Carl Hackenberg 16 March |
| Engels to Pablo Iglesias 16 March |
| Engels to Carl Hirsch 19 March |
| Engels to Ludwig Kugelman 19 March |
| Engels to Hermann Engels 20 March |
| Engels to Vera Zasulich 22 March |
| Engels to Karl Kautsky 25 March |
| Engels to Laura Lafargue 28 March |
| Engels to Karl Kautsky 1 April |
| Engels to Harry Quelch 2 April |
| Engels to Paul Lafargue 3 April |
| Engels to Richard Fischer 5 April |
| Engels to Conrad Schmidt 6 April |
| Engels to Stephan Bauer 10 April |
| Engels to Hermann Engels 12 April |
| Engels to Krystyu Rakovski 13 April |
| Engels to Richard Fischer 15 April |
| Engels to Laura Lafargue 17 April |
| Engels to Ludwig Kugelmann 18 April |
| Engels to Richard Fischer 18 April |
| Engels to Stanislaw Mendelson 23 April |
| Engels to Franz Mehring end April |
| Engels to Franz Mehring 9 May |
| Engels to Richard Fischer 9 May |
| Engels to Laura Lafargue 14 May |
| Engels to Ignaz Brand 20 May |
| Engels to Carl Hirsch 20 May |
| Engels to Karl Kautsky 21 May |
| Engels to Editors of Rheinische Zeitung 22 May
|
| Engels to Richard Fischer 29 May |
| Engels to Nikolai Danielson 4 June |
| Engels to Eduard Bernstein 18 June |
| Engels to Bolesaw Antoni Jedrzejowski 28 June
|
| Engels to Filippo Turai 28 June |
| Engels to Paul Lafargue 29 June |
| Engels to Richard Fischer 29 June |
| Engels to Louise Freyberger 1 July |
| Engels to Eduard Bernstein 4 July |
| Engels to Eleanor Marx-Aveling 4 July |
| Engels to Filippo Turati 4 July |
| Engels to Antonio Labriola 8 July |
| Engels to Eleanor Marx-Aveling 9 July |
| Engels to Laura Lafargue 23 July |