Chromolithography is a method for making multi-colour prints in lithography, and in theory includes all types of lithography that are printed in colour. However, in modern usage it is normally restricted to 19th-century works, and the higher quality examples from that period; almost all 21st-century colour printing uses lithography, but would not be described using the term chromolithography. When chromolithography is used to reproduce photographs, the term photochrome is frequently used. Lithography is a method of printing on flat surfaces using a flat printing plate instead of raised relief or recessed intaglio techniques.

Chromolithography became the most successful of several methods of colour printing developed in the 19th century. Other methods were developed by printers such as Jacob Christoph Le Blon, George Baxter and Edmund Evans, and mostly relied on using several woodblocks with different colours. Hand-colouring also remained important. For example, elements of the official British Ordnance Survey maps were coloured by hand by boys until 1875. The initial chromolithographic technique involved the use of multiple lithographic stones, one for each colour, and was still extremely expensive when done for the best quality results. Depending on the number of colours present, a chromolithograph could take even very skilled workers months to produce.

However much cheaper prints could be produced by simplifying the number of colours used, and reducing the detail in the image. Cheaper images, like advertisements, relied heavily on an initial black print (not always a lithograph), on which colours were then overprinted. To make an expensive reproduction print, once referred to as a "chromo", a lithographer, with a finished painting in front of him, gradually created and corrected the many stones using proofs to look as much as possible like the painting, sometimes using dozens of layers.

Oleograph is sometimes used as a synonym for a chromolithograph, but more properly refers to a chromolithograph that has then been treated to imitate the variable surface of an oil painting, either by brushing with varnish, or some form of embossing or stamping. The print is usually glued to canvas to further the imitation.

Lithography, including chromolithography, is a process based on the rejection of water by grease. The image is applied to stone, grained zinc or aluminium surfaces, with a grease-based crayon or ink. Limestone and zinc are two commonly used materials in the production of chromolithographs, as aluminium production was limited before the invention of the Hall-Heroult process. After the image is drawn onto one of these surfaces, the image is gummed-up with a gum arabic solution and weak nitric acid to protect the remaining surface before inking up the image with oil based transfer or printing ink. Before final printing, the image is proof printed and any errors corrected. In the direct form of printing, the inked image is transferred under pressure onto a sheet of paper using a flat-bed press. The offset indirect method uses a rubber-covered cylinder that transfers the image from the printing surface to the paper. Colours may be overprinted by using additional stones or plates to achieve a closer reproduction of the original. Accurate registration for multi-coloured work is achieved by the use of a key outline image and registration bars which are applied to each stone or plate before drawing the solid or tone image. Ben-Day medium uses a raised gelatin stipple image to give tone gradation. An air-brush sprays ink to give soft edges. These are just two methods used to achieve gradations of tone. The use of twelve overprinted colours would not be considered unusual. Each sheet of paper will therefore pass through the printing press as many times as there are colours in the final print. In order that each colour is placed in the right position, each stone or plate must be precisely 'registered,' or lined up, on the paper using a system of register marks.

Prints described as chromolithographs are typically smaller than posters and advertisements, both common types of colour lithographs in the later 19th century and subsequently, and are of finer quality, generally suitable for framing as prints. Autolithographs are prints where the artist draws and perhaps prints his own limited number of reproductions. This is the true lithographic art form.

Alois Senefelder, the inventor of lithography, introduced the subject of coloured lithography in his 1818 Vollstaendiges Lehrbuch der Steindruckerey (A Complete Course of Lithography), where he told of his plans to print using colour and explained the colours he wished to be able to print someday. Although Senefelder recorded plans for chromolithography, printers in other countries, such as France and England, were also trying to find a new way to print in colour. Godefroy Engelmann of Mulhouse in France was awarded a patent on chromolithography in July 1837, but there are disputes over whether chromolithography was already in use before this date, as some sources say, pointing to areas of printing such as the production of playing cards.

The first American chromolithograph—a portrait of Reverend F. W. P. Greenwood—was created by William Sharp in 1840. Many of the chromolithographs were created and purchased in urban areas. The prints were initially used as decoration in American parlours as well as for decoration within middle-class homes. They were prominent after the Civil War because of their low production costs and ability to be mass-produced, and because the methods allowed pictures to look more like hand-painted oil paintings. Production costs were only low if the chromolithographs were cheaply produced, but top-quality chromos were costly to produce because of the necessary months of work and the thousands of dollars' worth of equipment that had to be used.