You can see a full list of Darwin’s published work at the Complete Works of Charles Darwin Online website, this includes work of his that has been published after his death. The great thing is you can read it all online free of charge!

Below are his published books and major works which were published during Darwin’s lifetime (apart from his autobiography). They give you a glimpse of the range of topics Darwin worked on during his life. Most of Darwin's work however was intregrative, linking different fields and subjects.

The young Charles Darwin spent five years on board the H.M.S. Beagle, travelled round the world, seeing a great many things of interest to botanists, geologists and zoologists. He sent home letters to Henslow, his mentor in Cambridge, many of which were published while he was away. On his return he set about sorting his specimens and writing up his notes. The result was five books which covered a huge range of topics. Darwin’s Journal of Researches was originally published as a trio with accounts by the ship’s Captain Robert FitzRoy and previous captain Parker King. Darwin’s account proved much more readable than the others so was subsequently published alone. It’s an entertaining account of the voyage for a general audience and sold well. The other four are scientific works on the zoological and geological notes and specimens Darwin took.

• The Zoology of the Voyage of HMS Beagle (1835)
• Journal of Researches (aka Voyage of the Beagle) (1839)
• The Structure and Distribution of Coral Reefs (1842)
• Geological Observations on the Volcanic Islands Visited by the Voyage of H.M.S. Beagle (1844)
• Geological Observations and Distributions of Coral Reefs (1846) 

Darwin is most often associated with his revolutionary work on evolution. His theories of natural and sexual selection now underpin all biology. He had begun writing and reading about ‘transmutation’ (as species evolution was then known) when he returned from the Beagle Voyage in 1836 and wrote sketches of his theory of natural selection in 1842 and 1844. Originally he had planned a massive ‘big book’ on his theories; every time he tried to write a smaller version, it got too long as he tried to include all the masses of evidence he had collected on a huge range of different subjects. He was finally forced into publication when he received a letter from Alfred Russell Wallace, describing a theory nearly identical to his own. Under the advice of Charles Lyell and Joseph Hooker, Darwin's and Wallace’s theories were published together in 1858 in the Journal of the Proceedings of the Linnaean Society of London. Zoology 3 (20 August): 46-50. Darwin followed this up with an ‘abstract’ of his big book, On The Origin of Species in 1859. All his later books added to his basic treatise both in terms of detail and evidence; two books notably extended his theories. In The variation of animals and plants under domestication Darwin documents much more evidence of selection and evolution in domestic animals and plants and proposes his (failed) theory of inheritance of variation, Pangenesis. In The Descent of man, and selection in relation to sex he applies his theory to the evolution of humans and also introduces (with typically huge amounts of evidence) a new theory: sexual selection.

• On the Tendency of Species to Form Varieties; and on the Perpetuation of Varieties and Species by Natural Means of Selection (1858, jointly published with work by Alfred Russell Wallace)
• On The Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life (1859)
• The Variation of Animals and Plants Under Domestication (Vol I & II) (1868)
• The Descent of Man, and Selection in Relation to Sex (Vol I & II) (1871)

Darwin is not often associated with botany, and he himself was often modest about his botanical work, perhaps because he was friends with three great botanists in John Henslow, Joseph Hooker and Asa Gray. He actually published 6 books solely on plants, and evidence from botany played major roles in the evidence he used to support his theories in The Origin and The Variation. Darwin worked with his plants throughout his time at Down House, performing various experiments with them including cross fertilisation experiments, watching how they grow, playing music to them, and floating their seeds in salt water. His library was often full of jars of plant seeds in sea water, or seeds being germinated from animal droppings. His botanical books were popular and sold well, especially his work on the sex lives of orchids. They were scientifically important too; his work on orchids demonstrates an excellent example of adaptation by natural selection, and his work on climbing plants was important in paving the way for the discovery of the first plant hormone, auxin.

• On the Various Contrivances by which British and Foreign Orchids are Fertilised by Insects (1862)
• On the Movements and Habits of Climbing Plants (1865)
• Insectivorous plants (1875)
• The Effects of Cross and Self Fertilisation in the Vegetable Kingdom (1876)
• Different Forms of Flowers on Plants of the Same Species (1877)
• The Power of Movement in Plants (1880)

Darwin wrote widely about zoology. His early work on the Beagle was largely centred on zoology and palaeozoology, and he built his professional career with work on the barnacles. Throughout his work on the origin of species, variation and evolution he performed experiments and wrote about a wide range of zoological topics. As well as this, he wrote about more specific subjects: the barnacles, the evolution of humans, and variation in domestic animals especially pigeons, for example. Two books which aren’t included in the above categories are: The Expression of Emotions (1872) in which he argues that human expressions have evolved gradually and similar expressions can be seen in primates and other animals; and his final book, The Formation of Vegetable Mould in which Darwin returns to his first love, invertebrates, with an account on the behaviour, function and importance of earthworms.

• The Expression of Emotions in Man and Animals (1872)
• The Formation of Vegetable Mould, Through the Action of Worms (1881)

As well as his scientific work Darwin wrote two biographies. The first was of his grandfather Erasmus Darwin, who was a doctor, philosopher, poet and evolutionist. He formulated one of the earliest theories of evolution in his book Zoonomia. Darwin wrote a short account of his own life which was intended for family eyes only, in which he famously admits his lack of belief in Christianity. It was originally published by his son, Francis, omitting certain passages deemed too personal for the public, but has since been published in full.

• Life of Erasmus Darwin (1879)
• The Life and Letters of Charles Darwin, Including an Autobiographical Chapter (Edited by Francis Darwin, 1887)

Written by Stephen Montgomery