Two causes that led to the Non-Cooperation Movement were:
(i) The First World War led to a huge increase in defense expenditure and increased taxes. Forced recruitment caused widespread anger. Famine and epidemic affected the people badly. This outraged the people.
(ii) The Non-Cooperation Movement was a reaction to the oppressive policies of the British Indian government such as the Rowlatt Act and the Jallianwala Bagh massacre.