The first Partition of Bengal (1905) was a territorial reorganization of the Bengal Presidency implemented by the authorities of the British Raj. The reorganization separated the largely Muslim eastern areas from the largely Hindu western areas. Announced on 19 July 1905 by Lord Curzon, the then Viceroy of India, and implemented on 16 October 1905, it was undone a mere six years later.

The Hindus of West Bengal complained that the division would make them a minority in a province that would incorporate the province of Bihar and Orissa. Hindus were outraged at what they saw as a "divide and rule" policy,: 248–249  even though Curzon stressed it would produce administrative efficiency. The partition animated the Muslims to form their own national organization along communal lines. To appease Bengali sentiment, Bengal was reunited by Lord Hardinge in 1911, in response to the Swadeshi movement's riots in protest against the policy.