A concrete block was thrown through the window of a Rothwell pub on Saturday morning, causing extensive damage.
The incident happened sometime between 7 and 7.30am at the Rowell Charter Inn, in Sun Hill.
The concrete block was thrown into a ground floor window, causing a large amount of damage.
Witnesses are asked to phone Northamptonshire Police on 101. Alternatively, information can be given anonymously to Crimestoppers on 0800 555111.