The January Uprising (Polish: powstanie styczniowe, Lithuanian: 1863 m. sukilimas, Belarusian: Паўстанне 1863-1864 гадоў) was an uprising in the former Polish-Lithuanian Commonwealth (present-day Poland, Lithuania, Belarus, Latvia, parts of Ukraine, western Russia) against the Russian Empire. It began January 22, 1863, and lasted until the last insurgents were captured in 1865.

The uprising began as a spontaneous protest by young Poles against conscription into the Imperial Russian Army, and was soon joined by high-ranking Polish-Lithuanian officers and various politicians. The insurrectionists, severely outnumbered and lacking serious outside support, were forced to resort to guerrilla warfare tactics. They failed to win any major military victories or capture any major cities or fortresses, but they did blunt the effect of the Tsar's abolition of serfdom in the Russian partition, which had been designed to draw the support of peasants away from the nation. Severe reprisals against insurgents, such as public executions and deportations to Siberia, led many people to abandon armed struggle and turn instead to the idea of "organic work": economic and cultural self-improvement.