Mussorgsky was the son of a landowner but had peasant blood, his father's grandmother having been a serf. According to his autobiographical sketch, written in 1881, Mussorgsky learned about Russian fairy tales from his nurse. “This early familiarity with the spirit of the people, with the way they lived, lent the first and greatest impetus to my musical improvisations.” His mother, herself an excellent pianist, gave Modest his first piano lessons, and at seven he could play some of Franz Liszt's simpler pieces.

In August 1849 his father took Modest and his other son, Filaret, to St. Petersburg, where Modest attended the Peter-Paul School in preparation for a military career. At the same time, mindful of Modest's musical bent, their father entrusted the boys to Anton Gerke, future professor of music at the St. Petersburg Conservatory.

In 1852 Mussorgsky entered the School for Cadets of the Guard. There, in his first year he composed his Podpraporshchik (Porte-Enseigne Polka), published at his father's expense. Although not the most industrious of students, he gave proof of tremendous curiosity and wide-ranging intellectual interests.

In 1856, by now a lieutenant, Mussorgsky joined the Preobrazhensky Guards, one of Russia's most aristocratic regiments, where he made the acquaintance of several music-loving officers who were habitués of the Italian theatre. During this same period he came to know Aleksandr Borodin (Borodin, Aleksandr), a fellow officer who was to become another important Russian composer. Borodin has provided a very vivid picture of the musician:

During the winter of 1856 a regimental comrade introduced Mussorgsky into the home of the Russian composer Aleksandr Dargomyzhsky (Dargomyzhsky, Aleksandr). At one of the musicales there, Mussorgsky discovered the music of the seminal Russian composer Mikhail Glinka (Glinka, Mikhail), and this quickened his own Russophile inclinations. Three years later, in June 1859, he saw the Moscow Kremlin for the first time, an important experience that represented his first “physical” communion with Russian history. Through Dargomyzhsky, Mussorgsky met another composer, Mily Balakirev (Balakirev, Mily), who became his teacher. Since the death of their father (in 1853), the Mussorgsky brothers had seen their poorly administered patrimony decrease substantially. With the freeing of the serfs in 1861, it vanished. Having decided to devote himself to music, Modest Mussorgsky had quit the army three years earlier and since 1863 had been working as a civil servant in the Ministry of Communications. His distressing financial troubles date from that time, and he had to seek the help of moneylenders.

Mussorgsky achieved artistic maturity in 1866 with a series of remarkable songs about ordinary people such as “Darling Savishna,” “Hopak,” and “The Seminarist,” and an even larger series appeared the following year. Another work dating from this time is the symphonic poem Ivanova noch na Lysoy gore (1867; Night on Bald Mountain). In 1868 he reached the height of his conceptual powers in composition with the first song of his incomparable cycle Detskaya (The Nursery) and a setting of the first few scenes of Nikolay Gogol's Zhenitba (The Marriage).

In 1869 he began his great work Boris Godunov to his own libretto based on the drama by Aleksandr Pushkin (Pushkin, Aleksandr Sergeyevich). The first version, completed in December 1869, was rejected by the advisory committee of the imperial theatres because it lacked a prima donna role. In response, the composer subjected the opera to a thorough revision and in 1872 put the finishing touches to the second version, adding the roles of Marina and Rangoni as well as several new episodes. The first production of Boris took place on February 8, 1874, at St. Petersburg and was a success.

In 1865, after the death of his mother, he lived with his brother, then shared a small flat with the Russian composer Nikolay Rimsky-Korsakov (Rimsky-Korsakov, Nikolay) until 1872, when his colleague married. Left very much alone, Mussorgsky began to drink to excess, although the composition of the opera Khovanshchina perhaps offered some distraction (left unfinished at his death, this opera was completed by Rimsky-Korsakov). Mussorgsky then found a companion in the person of a distant relative, Arseny Golenishchev-Kutuzov. This impoverished 25-year-old poet inspired Mussorgsky's two cycles of melancholy melodies, Bez solntsa (Sunless) and Pesni i plyaski smerti (Songs and Dances of Death). At that time Mussorgsky was haunted by the spectre of death—he himself had only seven more years to live. The death of another friend, the painter Victor Hartmann, inspired Mussorgsky to write the piano suite Kartinki s vystavki (Pictures from an Exhibition; orchestrated in 1922 by the French composer Maurice Ravel (Ravel, Maurice)).

The last few years of Mussorgsky's life were dominated by his alcoholism and by a solitude made all the more painful by Golenishchev-Kutuzov's marriage. Nonetheless, the composer began his opera Sorochinskaya yarmarka (unfinished; Sorochintsy Fair), inspired by Gogol's tale. As the accompanist of an aging singer, Darya Leonova, Mussorgsky departed on a lengthy concert tour of southern Russia and the Crimea. On his return he tried teaching at a small school of music in St. Petersburg.

On February 24, 1881, three successive attacks of alcoholic epilepsy laid him low. His friends took him to a hospital where for a time his health improved sufficiently for one of the leading Russian artists of the day, Ilya Repin (Repin, Ilya Yefimovich), to paint a famous portrait of him. Mussorgsky's health was irreparably damaged, however, and he died within a month, shortly after his 42nd birthday.

Mussorgsky's importance to and influence on later composers are quite out of proportion to his relatively small output. Few composers were less derivative, or evolved so original and bold a style. The 65 songs he composed, many to his own texts, describe scenes of Russian (Russia) life with great vividness and insight and realistically reproduce the inflections of the spoken Russian language. Mussorgsky's operas Boris Godunov and to a lesser extent Khovanshchina display his dramatic technique of setting sharply characterized individuals against the background of country and people. His power of musical portrayal, his strong characterizations, and the importance he assigned to the role of the chorus establish Boris Godunov as a masterpiece. From a technical standpoint, Mussorgsky's unorthodox use of tonality and harmony and his method of fusing arioso and recitative provide Boris Godunov with great dramatic intensity.

Shortly after Mussorgsky's death, Rimsky-Korsakov prepared Mussorgsky's works for publication, in the process purging them of what he considered to be their harmonic eccentricities and instrumental weaknesses. Rimsky-Korsakov's widely performed edition of Boris Godunov is the best known of these works. From roughly 1908, however, after the production of Rimsky-Korsakov's version of Boris Godunov at the Paris Opera, there was a growing demand for the original versions of Mussorgsky's works, which were made available beginning in 1928 in a collected edition edited by Paul Lamm. This edition displayed Mussorgsky's original orchestration for Boris Godunov, which is as stark and economical as his unorthodox harmony.